diff --git a/.github/workflows/benchmark.yml b/.github/workflows/benchmark.yml
index f9699ac80f24..8671cff054bb 100644
--- a/.github/workflows/benchmark.yml
+++ b/.github/workflows/benchmark.yml
@@ -33,7 +33,7 @@ on:
       scala:
         description: 'Scala version: 2.12 or 2.13'
         required: true
-        default: '2.13'
+        default: '2.12'
       failfast:
         description: 'Failfast: true or false'
         required: true
@@ -182,7 +182,7 @@ jobs:
           "`find . -name 'spark-core*-SNAPSHOT-tests.jar'`" \
           "${{ github.event.inputs.class }}"
         # Revert to default Scala version to clean up unnecessary git diff
-        dev/change-scala-version.sh 2.13
+        dev/change-scala-version.sh 2.12
         # To keep the directory structure and file permissions, tar them
         # See also https://github.com/actions/upload-artifact#maintaining-file-permissions-and-case-sensitive-files
         echo "Preparing the benchmark results:"
diff --git a/.github/workflows/build_scala212.yml b/.github/workflows/build_scala213.yml
similarity index 93%
rename from .github/workflows/build_scala212.yml
rename to .github/workflows/build_scala213.yml
index 89d22db72f0f..cae0981ee1e8 100644
--- a/.github/workflows/build_scala212.yml
+++ b/.github/workflows/build_scala213.yml
@@ -17,7 +17,7 @@
 # under the License.
 #
 
-name: "Build (master, Scala 2.12, Hadoop 3, JDK 8)"
+name: "Build (master, Scala 2.13, Hadoop 3, JDK 8)"
 
 on:
   schedule:
@@ -36,7 +36,7 @@ jobs:
       hadoop: hadoop3
       envs: >-
         {
-          "SCALA_PROFILE": "scala2.12"
+          "SCALA_PROFILE": "scala2.13"
         }
       jobs: >-
         {
diff --git a/assembly/pom.xml b/assembly/pom.xml
index d4d7a1db4a29..09d6bd8a33f7 100644
--- a/assembly/pom.xml
+++ b/assembly/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-assembly_2.13</artifactId>
+  <artifactId>spark-assembly_2.12</artifactId>
   <name>Spark Project Assembly</name>
   <url>https://spark.apache.org/</url>
   <packaging>pom</packaging>
diff --git a/common/kvstore/pom.xml b/common/kvstore/pom.xml
index 69f9f186e088..bef8303874b2 100644
--- a/common/kvstore/pom.xml
+++ b/common/kvstore/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-kvstore_2.13</artifactId>
+  <artifactId>spark-kvstore_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Local DB</name>
   <url>https://spark.apache.org/</url>
diff --git a/common/network-common/pom.xml b/common/network-common/pom.xml
index 9f90d12216e6..8a63e999c53c 100644
--- a/common/network-common/pom.xml
+++ b/common/network-common/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-network-common_2.13</artifactId>
+  <artifactId>spark-network-common_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Networking</name>
   <url>https://spark.apache.org/</url>
diff --git a/common/network-shuffle/pom.xml b/common/network-shuffle/pom.xml
index 864f1cc2d371..a8bde14a259f 100644
--- a/common/network-shuffle/pom.xml
+++ b/common/network-shuffle/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-network-shuffle_2.13</artifactId>
+  <artifactId>spark-network-shuffle_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Shuffle Streaming Service</name>
   <url>https://spark.apache.org/</url>
diff --git a/common/network-yarn/pom.xml b/common/network-yarn/pom.xml
index c19ac33afa5c..671d5cb7e017 100644
--- a/common/network-yarn/pom.xml
+++ b/common/network-yarn/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-network-yarn_2.13</artifactId>
+  <artifactId>spark-network-yarn_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project YARN Shuffle Service</name>
   <url>https://spark.apache.org/</url>
diff --git a/common/sketch/pom.xml b/common/sketch/pom.xml
index 6cf1a4fb83e5..4cc597519c3d 100644
--- a/common/sketch/pom.xml
+++ b/common/sketch/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-sketch_2.13</artifactId>
+  <artifactId>spark-sketch_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Sketch</name>
   <url>https://spark.apache.org/</url>
diff --git a/common/tags/pom.xml b/common/tags/pom.xml
index 1eb8352e32df..9a44c847d8a0 100644
--- a/common/tags/pom.xml
+++ b/common/tags/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-tags_2.13</artifactId>
+  <artifactId>spark-tags_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Tags</name>
   <url>https://spark.apache.org/</url>
diff --git a/common/unsafe/pom.xml b/common/unsafe/pom.xml
index e37f1b80a504..a61f00084eb6 100644
--- a/common/unsafe/pom.xml
+++ b/common/unsafe/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-unsafe_2.13</artifactId>
+  <artifactId>spark-unsafe_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Unsafe</name>
   <url>https://spark.apache.org/</url>
diff --git a/common/utils/pom.xml b/common/utils/pom.xml
index ee10a6061829..36cfceed931e 100644
--- a/common/utils/pom.xml
+++ b/common/utils/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-common-utils_2.13</artifactId>
+  <artifactId>spark-common-utils_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Common Utils</name>
   <url>https://spark.apache.org/</url>
diff --git a/connector/avro/pom.xml b/connector/avro/pom.xml
index 7087fdbccd04..597e3c2235f7 100644
--- a/connector/avro/pom.xml
+++ b/connector/avro/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-avro_2.13</artifactId>
+  <artifactId>spark-avro_2.12</artifactId>
   <properties>
     <sbt.project.name>avro</sbt.project.name>
   </properties>
@@ -70,12 +70,12 @@
       <groupId>org.apache.spark</groupId>
       <artifactId>spark-tags_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
     <dependency>
       <groupId>org.tukaani</groupId>
       <artifactId>xz</artifactId>
diff --git a/connector/connect/client/jvm/pom.xml b/connector/connect/client/jvm/pom.xml
index 8dc4c3b7a19d..4d0a43793296 100644
--- a/connector/connect/client/jvm/pom.xml
+++ b/connector/connect/client/jvm/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-connect-client-jvm_2.13</artifactId>
+  <artifactId>spark-connect-client-jvm_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Connect Client</name>
   <url>https://spark.apache.org/</url>
diff --git a/connector/connect/common/pom.xml b/connector/connect/common/pom.xml
index fcd72480e0ef..06076646df7a 100644
--- a/connector/connect/common/pom.xml
+++ b/connector/connect/common/pom.xml
@@ -21,12 +21,12 @@
     <modelVersion>4.0.0</modelVersion>
     <parent>
         <groupId>org.apache.spark</groupId>
-        <artifactId>spark-parent_2.13</artifactId>
+        <artifactId>spark-parent_2.12</artifactId>
         <version>3.5.0-SNAPSHOT</version>
         <relativePath>../../../pom.xml</relativePath>
     </parent>
 
-    <artifactId>spark-connect-common_2.13</artifactId>
+    <artifactId>spark-connect-common_2.12</artifactId>
     <packaging>jar</packaging>
     <name>Spark Project Connect Common</name>
     <url>https://spark.apache.org/</url>
diff --git a/connector/connect/server/pom.xml b/connector/connect/server/pom.xml
index f3b43e14cdab..f9dc40ce85a4 100644
--- a/connector/connect/server/pom.xml
+++ b/connector/connect/server/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-connect_2.13</artifactId>
+  <artifactId>spark-connect_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Connect Server</name>
   <url>https://spark.apache.org/</url>
@@ -156,12 +156,12 @@
         </exclusion>
       </exclusions>
     </dependency>
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
     <dependency>
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
diff --git a/connector/docker-integration-tests/pom.xml b/connector/docker-integration-tests/pom.xml
index e40269838522..cc549487a8b5 100644
--- a/connector/docker-integration-tests/pom.xml
+++ b/connector/docker-integration-tests/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-docker-integration-tests_2.13</artifactId>
+  <artifactId>spark-docker-integration-tests_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Docker Integration Tests</name>
   <url>https://spark.apache.org/</url>
diff --git a/connector/kafka-0-10-assembly/pom.xml b/connector/kafka-0-10-assembly/pom.xml
index f339e8c2e4fd..340974cc789b 100644
--- a/connector/kafka-0-10-assembly/pom.xml
+++ b/connector/kafka-0-10-assembly/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-streaming-kafka-0-10-assembly_2.13</artifactId>
+  <artifactId>spark-streaming-kafka-0-10-assembly_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Integration for Kafka 0.10 Assembly</name>
   <url>https://spark.apache.org/</url>
diff --git a/connector/kafka-0-10-sql/pom.xml b/connector/kafka-0-10-sql/pom.xml
index f5a12b61c2be..fdd1196cd446 100644
--- a/connector/kafka-0-10-sql/pom.xml
+++ b/connector/kafka-0-10-sql/pom.xml
@@ -20,13 +20,13 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
   <groupId>org.apache.spark</groupId>
-  <artifactId>spark-sql-kafka-0-10_2.13</artifactId>
+  <artifactId>spark-sql-kafka-0-10_2.12</artifactId>
   <properties>
     <sbt.project.name>sql-kafka-0-10</sbt.project.name>
   </properties>
@@ -74,12 +74,12 @@
       <type>test-jar</type>
       <scope>test</scope>
     </dependency>
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
     <dependency>
       <groupId>org.apache.kafka</groupId>
       <artifactId>kafka-clients</artifactId>
diff --git a/connector/kafka-0-10-token-provider/pom.xml b/connector/kafka-0-10-token-provider/pom.xml
index b3c0889d9475..3256130c50f3 100644
--- a/connector/kafka-0-10-token-provider/pom.xml
+++ b/connector/kafka-0-10-token-provider/pom.xml
@@ -20,13 +20,13 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
   <groupId>org.apache.spark</groupId>
-  <artifactId>spark-token-provider-kafka-0-10_2.13</artifactId>
+  <artifactId>spark-token-provider-kafka-0-10_2.12</artifactId>
   <properties>
     <sbt.project.name>token-provider-kafka-0-10</sbt.project.name>
   </properties>
diff --git a/connector/kafka-0-10/pom.xml b/connector/kafka-0-10/pom.xml
index f1820bb595a2..706eb2dd2c39 100644
--- a/connector/kafka-0-10/pom.xml
+++ b/connector/kafka-0-10/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-streaming-kafka-0-10_2.13</artifactId>
+  <artifactId>spark-streaming-kafka-0-10_2.12</artifactId>
   <properties>
     <sbt.project.name>streaming-kafka-0-10</sbt.project.name>
   </properties>
@@ -59,12 +59,12 @@
       <type>test-jar</type>
       <scope>test</scope>
     </dependency>
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
     <dependency>
       <groupId>org.apache.kafka</groupId>
       <artifactId>kafka-clients</artifactId>
diff --git a/connector/kinesis-asl-assembly/pom.xml b/connector/kinesis-asl-assembly/pom.xml
index 2cba2668f049..cd5c0393f6f8 100644
--- a/connector/kinesis-asl-assembly/pom.xml
+++ b/connector/kinesis-asl-assembly/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-streaming-kinesis-asl-assembly_2.13</artifactId>
+  <artifactId>spark-streaming-kinesis-asl-assembly_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Kinesis Assembly</name>
   <url>https://spark.apache.org/</url>
diff --git a/connector/kinesis-asl/pom.xml b/connector/kinesis-asl/pom.xml
index af9cd4b7ec96..c70a073e7340 100644
--- a/connector/kinesis-asl/pom.xml
+++ b/connector/kinesis-asl/pom.xml
@@ -19,13 +19,13 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
   <!-- Kinesis integration is not included by default due to ASL-licensed code. -->
-  <artifactId>spark-streaming-kinesis-asl_2.13</artifactId>
+  <artifactId>spark-streaming-kinesis-asl_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Kinesis Integration</name>
 
diff --git a/connector/protobuf/pom.xml b/connector/protobuf/pom.xml
index c99b9a060874..e85f07841dfa 100644
--- a/connector/protobuf/pom.xml
+++ b/connector/protobuf/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-protobuf_2.13</artifactId>
+  <artifactId>spark-protobuf_2.12</artifactId>
   <properties>
     <sbt.project.name>protobuf</sbt.project.name>
   </properties>
@@ -70,12 +70,12 @@
       <groupId>org.apache.spark</groupId>
       <artifactId>spark-tags_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
     <dependency>
       <groupId>com.google.protobuf</groupId>
       <artifactId>protobuf-java</artifactId>
diff --git a/connector/spark-ganglia-lgpl/pom.xml b/connector/spark-ganglia-lgpl/pom.xml
index 00f4769fd60a..c0dcde135584 100644
--- a/connector/spark-ganglia-lgpl/pom.xml
+++ b/connector/spark-ganglia-lgpl/pom.xml
@@ -19,13 +19,13 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
   <!-- Ganglia integration is not included by default due to LGPL-licensed code -->
-  <artifactId>spark-ganglia-lgpl_2.13</artifactId>
+  <artifactId>spark-ganglia-lgpl_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Ganglia Integration</name>
 
diff --git a/core/pom.xml b/core/pom.xml
index 79bf8a216355..6519b46d96e3 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-core_2.13</artifactId>
+  <artifactId>spark-core_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Core</name>
   <url>https://spark.apache.org/</url>
@@ -35,12 +35,12 @@
   </properties>
   
   <dependencies>
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
     <dependency>
       <groupId>org.apache.avro</groupId>
       <artifactId>avro</artifactId>
diff --git a/dev/deps/spark-deps-hadoop-3-hive-2.3 b/dev/deps/spark-deps-hadoop-3-hive-2.3
index 99b627af3407..830c391046c9 100644
--- a/dev/deps/spark-deps-hadoop-3-hive-2.3
+++ b/dev/deps/spark-deps-hadoop-3-hive-2.3
@@ -5,7 +5,7 @@ RoaringBitmap/0.9.44//RoaringBitmap-0.9.44.jar
 ST4/4.0.4//ST4-4.0.4.jar
 activation/1.1.1//activation-1.1.1.jar
 aircompressor/0.21//aircompressor-0.21.jar
-algebra_2.13/2.8.0//algebra_2.13-2.8.0.jar
+algebra_2.12/2.0.1//algebra_2.12-2.0.1.jar
 aliyun-java-sdk-core/4.5.10//aliyun-java-sdk-core-4.5.10.jar
 aliyun-java-sdk-kms/2.11.0//aliyun-java-sdk-kms-2.11.0.jar
 aliyun-java-sdk-ram/3.1.0//aliyun-java-sdk-ram-3.1.0.jar
@@ -30,11 +30,11 @@ azure-keyvault-core/1.0.0//azure-keyvault-core-1.0.0.jar
 azure-storage/7.0.1//azure-storage-7.0.1.jar
 blas/3.0.3//blas-3.0.3.jar
 bonecp/0.8.0.RELEASE//bonecp-0.8.0.RELEASE.jar
-breeze-macros_2.13/2.1.0//breeze-macros_2.13-2.1.0.jar
-breeze_2.13/2.1.0//breeze_2.13-2.1.0.jar
-cats-kernel_2.13/2.8.0//cats-kernel_2.13-2.8.0.jar
+breeze-macros_2.12/2.1.0//breeze-macros_2.12-2.1.0.jar
+breeze_2.12/2.1.0//breeze_2.12-2.1.0.jar
+cats-kernel_2.12/2.1.1//cats-kernel_2.12-2.1.1.jar
 chill-java/0.10.0//chill-java-0.10.0.jar
-chill_2.13/0.10.0//chill_2.13-0.10.0.jar
+chill_2.12/0.10.0//chill_2.12-0.10.0.jar
 commons-cli/1.5.0//commons-cli-1.5.0.jar
 commons-codec/1.15//commons-codec-1.15.jar
 commons-collections/3.2.2//commons-collections-3.2.2.jar
@@ -104,7 +104,7 @@ jackson-databind/2.15.1//jackson-databind-2.15.1.jar
 jackson-dataformat-cbor/2.15.1//jackson-dataformat-cbor-2.15.1.jar
 jackson-dataformat-yaml/2.15.1//jackson-dataformat-yaml-2.15.1.jar
 jackson-datatype-jsr310/2.15.1//jackson-datatype-jsr310-2.15.1.jar
-jackson-module-scala_2.13/2.15.1//jackson-module-scala_2.13-2.15.1.jar
+jackson-module-scala_2.12/2.15.1//jackson-module-scala_2.12-2.15.1.jar
 jakarta.annotation-api/1.3.5//jakarta.annotation-api-1.3.5.jar
 jakarta.inject/2.6.1//jakarta.inject-2.6.1.jar
 jakarta.servlet-api/4.0.3//jakarta.servlet-api-4.0.3.jar
@@ -129,16 +129,14 @@ jettison/1.5.3//jettison-1.5.3.jar
 jetty-util-ajax/9.4.51.v20230217//jetty-util-ajax-9.4.51.v20230217.jar
 jetty-util/9.4.51.v20230217//jetty-util-9.4.51.v20230217.jar
 jline/2.14.6//jline-2.14.6.jar
-jline/3.21.0//jline-3.21.0.jar
-jna/5.9.0//jna-5.9.0.jar
 joda-time/2.12.5//joda-time-2.12.5.jar
 jodd-core/3.5.2//jodd-core-3.5.2.jar
 jpam/1.1//jpam-1.1.jar
 json/1.8//json-1.8.jar
-json4s-ast_2.13/3.7.0-M11//json4s-ast_2.13-3.7.0-M11.jar
-json4s-core_2.13/3.7.0-M11//json4s-core_2.13-3.7.0-M11.jar
-json4s-jackson_2.13/3.7.0-M11//json4s-jackson_2.13-3.7.0-M11.jar
-json4s-scalap_2.13/3.7.0-M11//json4s-scalap_2.13-3.7.0-M11.jar
+json4s-ast_2.12/3.7.0-M11//json4s-ast_2.12-3.7.0-M11.jar
+json4s-core_2.12/3.7.0-M11//json4s-core_2.12-3.7.0-M11.jar
+json4s-jackson_2.12/3.7.0-M11//json4s-jackson_2.12-3.7.0-M11.jar
+json4s-scalap_2.12/3.7.0-M11//json4s-scalap_2.12-3.7.0-M11.jar
 jsr305/3.0.0//jsr305-3.0.0.jar
 jta/1.1//jta-1.1.jar
 jul-to-slf4j/2.0.7//jul-to-slf4j-2.0.7.jar
@@ -226,22 +224,21 @@ pickle/1.3//pickle-1.3.jar
 py4j/0.10.9.7//py4j-0.10.9.7.jar
 remotetea-oncrpc/1.1.2//remotetea-oncrpc-1.1.2.jar
 rocksdbjni/8.1.1.1//rocksdbjni-8.1.1.1.jar
-scala-collection-compat_2.13/2.7.0//scala-collection-compat_2.13-2.7.0.jar
-scala-compiler/2.13.8//scala-compiler-2.13.8.jar
-scala-library/2.13.8//scala-library-2.13.8.jar
-scala-parallel-collections_2.13/1.0.4//scala-parallel-collections_2.13-1.0.4.jar
-scala-parser-combinators_2.13/2.2.0//scala-parser-combinators_2.13-2.2.0.jar
-scala-reflect/2.13.8//scala-reflect-2.13.8.jar
-scala-xml_2.13/2.1.0//scala-xml_2.13-2.1.0.jar
+scala-collection-compat_2.12/2.7.0//scala-collection-compat_2.12-2.7.0.jar
+scala-compiler/2.12.17//scala-compiler-2.12.17.jar
+scala-library/2.12.17//scala-library-2.12.17.jar
+scala-parser-combinators_2.12/2.2.0//scala-parser-combinators_2.12-2.2.0.jar
+scala-reflect/2.12.17//scala-reflect-2.12.17.jar
+scala-xml_2.12/2.1.0//scala-xml_2.12-2.1.0.jar
 shims/0.9.44//shims-0.9.44.jar
 slf4j-api/2.0.7//slf4j-api-2.0.7.jar
 snakeyaml-engine/2.6//snakeyaml-engine-2.6.jar
 snakeyaml/2.0//snakeyaml-2.0.jar
 snappy-java/1.1.10.0//snappy-java-1.1.10.0.jar
-spire-macros_2.13/0.18.0//spire-macros_2.13-0.18.0.jar
-spire-platform_2.13/0.18.0//spire-platform_2.13-0.18.0.jar
-spire-util_2.13/0.18.0//spire-util_2.13-0.18.0.jar
-spire_2.13/0.18.0//spire_2.13-0.18.0.jar
+spire-macros_2.12/0.17.0//spire-macros_2.12-0.17.0.jar
+spire-platform_2.12/0.17.0//spire-platform_2.12-0.17.0.jar
+spire-util_2.12/0.17.0//spire-util_2.12-0.17.0.jar
+spire_2.12/0.17.0//spire_2.12-0.17.0.jar
 stax-api/1.0.1//stax-api-1.0.1.jar
 stream/2.9.6//stream-2.9.6.jar
 super-csv/2.2.0//super-csv-2.2.0.jar
diff --git a/dev/mima b/dev/mima
index 32c3718e4ccc..4a9e343b0a78 100755
--- a/dev/mima
+++ b/dev/mima
@@ -24,9 +24,9 @@ set -e
 FWDIR="$(cd "`dirname "$0"`"/..; pwd)"
 cd "$FWDIR"
 
-SPARK_PROFILES=${1:-"-Pscala-2.13 -Pmesos -Pkubernetes -Pyarn -Pspark-ganglia-lgpl -Pkinesis-asl -Phive-thriftserver -Phive"}
-TOOLS_CLASSPATH="$(build/sbt -Pscala-2.13 -DcopyDependencies=false "export tools/fullClasspath" | grep jar | tail -n1)"
-OLD_DEPS_CLASSPATH="$(build/sbt -Pscala-2.13 -DcopyDependencies=false $SPARK_PROFILES "export oldDeps/fullClasspath" | grep jar | tail -n1)"
+SPARK_PROFILES=${1:-"-Pmesos -Pkubernetes -Pyarn -Pspark-ganglia-lgpl -Pkinesis-asl -Phive-thriftserver -Phive"}
+TOOLS_CLASSPATH="$(build/sbt -DcopyDependencies=false "export tools/fullClasspath" | grep jar | tail -n1)"
+OLD_DEPS_CLASSPATH="$(build/sbt -DcopyDependencies=false $SPARK_PROFILES "export oldDeps/fullClasspath" | grep jar | tail -n1)"
 
 rm -f .generated-mima*
 
@@ -42,7 +42,7 @@ $JAVA_CMD \
   -cp "$TOOLS_CLASSPATH:$OLD_DEPS_CLASSPATH" \
   org.apache.spark.tools.GenerateMIMAIgnore
 
-echo -e "q\n" | build/sbt -Pscala-2.13 -mem 5120 -DcopyDependencies=false "$@" mimaReportBinaryIssues | grep -v -e "info.*Resolving"
+echo -e "q\n" | build/sbt -mem 5120 -DcopyDependencies=false "$@" mimaReportBinaryIssues | grep -v -e "info.*Resolving"
 ret_val=$?
 
 if [ $ret_val != 0 ]; then
diff --git a/dev/test-dependencies.sh b/dev/test-dependencies.sh
index 07da6497b97d..d7967ac3afa9 100755
--- a/dev/test-dependencies.sh
+++ b/dev/test-dependencies.sh
@@ -62,7 +62,7 @@ SCALA_BINARY_VERSION=$($MVN -q \
     -Dexec.args='${scala.binary.version}' \
     --non-recursive \
     org.codehaus.mojo:exec-maven-plugin:1.6.0:exec | grep -E '[0-9]+\.[0-9]+')
-if [[ "$SCALA_BINARY_VERSION" != "2.13" ]]; then
+if [[ "$SCALA_BINARY_VERSION" != "2.12" ]]; then
   echo "Skip dependency testing on $SCALA_BINARY_VERSION"
   exit 0
 fi
diff --git a/docs/_plugins/copy_api_dirs.rb b/docs/_plugins/copy_api_dirs.rb
index 9cb073ef1e00..28d5e0d82c93 100644
--- a/docs/_plugins/copy_api_dirs.rb
+++ b/docs/_plugins/copy_api_dirs.rb
@@ -26,8 +26,8 @@
     curr_dir = pwd
     cd("..")
 
-    puts "Running 'build/sbt -Pscala-2.13 -Pkinesis-asl clean compile unidoc' from " + pwd + "; this may take a few minutes..."
-    system("build/sbt -Pscala-2.13 -Pkinesis-asl clean compile unidoc") || raise("Unidoc generation failed")
+    puts "Running 'build/sbt -Pkinesis-asl clean compile unidoc' from " + pwd + "; this may take a few minutes..."
+    system("build/sbt -Pkinesis-asl clean compile unidoc") || raise("Unidoc generation failed")
 
     puts "Moving back into docs dir."
     cd("docs")
@@ -37,7 +37,7 @@
 
     # Copy over the unified ScalaDoc for all projects to api/scala.
     # This directory will be copied over to _site when `jekyll` command is run.
-    source = "../target/scala-2.13/unidoc"
+    source = "../target/scala-2.12/unidoc"
     dest = "api/scala"
 
     puts "Making directory " + dest
@@ -119,8 +119,8 @@
     puts "Moving to project root and building API docs."
     cd("..")
 
-    puts "Running 'build/sbt -Pscala-2.13 clean package -Phive' from " + pwd + "; this may take a few minutes..."
-    system("build/sbt -Pscala-2.13 clean package -Phive") || raise("PySpark doc generation failed")
+    puts "Running 'build/sbt clean package -Phive' from " + pwd + "; this may take a few minutes..."
+    system("build/sbt clean package -Phive") || raise("PySpark doc generation failed")
 
     puts "Moving back into docs dir."
     cd("docs")
@@ -165,8 +165,8 @@
       puts "Moving to project root and building API docs."
       cd("..")
 
-      puts "Running 'build/sbt -Pscala-2.13 clean package -Phive' from " + pwd + "; this may take a few minutes..."
-      system("build/sbt -Pscala-2.13 clean package -Phive") || raise("SQL doc generation failed")
+      puts "Running 'build/sbt clean package -Phive' from " + pwd + "; this may take a few minutes..."
+      system("build/sbt clean package -Phive") || raise("SQL doc generation failed")
 
       puts "Moving back into docs dir."
       cd("docs")
diff --git a/examples/pom.xml b/examples/pom.xml
index 57e41724bdca..e8f22b995fde 100644
--- a/examples/pom.xml
+++ b/examples/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-examples_2.13</artifactId>
+  <artifactId>spark-examples_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Examples</name>
   <url>https://spark.apache.org/</url>
diff --git a/graphx/pom.xml b/graphx/pom.xml
index 5d01dd06c0ec..48baeb9a8756 100644
--- a/graphx/pom.xml
+++ b/graphx/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-graphx_2.13</artifactId>
+  <artifactId>spark-graphx_2.12</artifactId>
   <properties>
     <sbt.project.name>graphx</sbt.project.name>
   </properties>
diff --git a/hadoop-cloud/pom.xml b/hadoop-cloud/pom.xml
index 21c1e0fee1dd..02e7675df286 100644
--- a/hadoop-cloud/pom.xml
+++ b/hadoop-cloud/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-hadoop-cloud_2.13</artifactId>
+  <artifactId>spark-hadoop-cloud_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Hadoop Cloud Integration</name>
   <description>
diff --git a/launcher/pom.xml b/launcher/pom.xml
index 0bc3ae20ee18..aba7ee82d53c 100644
--- a/launcher/pom.xml
+++ b/launcher/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-launcher_2.13</artifactId>
+  <artifactId>spark-launcher_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Launcher</name>
   <url>https://spark.apache.org/</url>
diff --git a/mllib-local/pom.xml b/mllib-local/pom.xml
index 83ca643f43bc..00c16a8b6a54 100644
--- a/mllib-local/pom.xml
+++ b/mllib-local/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-mllib-local_2.13</artifactId>
+  <artifactId>spark-mllib-local_2.12</artifactId>
   <properties>
     <sbt.project.name>mllib-local</sbt.project.name>
   </properties>
diff --git a/mllib/pom.xml b/mllib/pom.xml
index 07290124273f..73af83c75868 100644
--- a/mllib/pom.xml
+++ b/mllib/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-mllib_2.13</artifactId>
+  <artifactId>spark-mllib_2.12</artifactId>
   <properties>
     <sbt.project.name>mllib</sbt.project.name>
   </properties>
@@ -91,12 +91,12 @@
       <type>test-jar</type>
       <scope>test</scope>
     </dependency>
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
     <dependency>
       <groupId>org.scalanlp</groupId>
       <artifactId>breeze_${scala.binary.version}</artifactId>
diff --git a/pom.xml b/pom.xml
index acac91f8d33c..8bf01db85a95 100644
--- a/pom.xml
+++ b/pom.xml
@@ -25,7 +25,7 @@
     <version>18</version>
   </parent>
   <groupId>org.apache.spark</groupId>
-  <artifactId>spark-parent_2.13</artifactId>
+  <artifactId>spark-parent_2.12</artifactId>
   <version>3.5.0-SNAPSHOT</version>
   <packaging>pom</packaging>
   <name>Spark Project Parent POM</name>
@@ -167,8 +167,8 @@
     <!-- managed up from 3.2.1 for SPARK-11652 -->
     <commons.collections.version>3.2.2</commons.collections.version>
     <commons.collections4.version>4.4</commons.collections4.version>
-    <scala.version>2.13.8</scala.version>
-    <scala.binary.version>2.13</scala.binary.version>
+    <scala.version>2.12.17</scala.version>
+    <scala.binary.version>2.12</scala.binary.version>
     <scalatest-maven-plugin.version>2.2.0</scalatest-maven-plugin.version>
     <!-- dont update scala-maven-plugin to version 4.8.1 SPARK-42809 and SPARK-43595 -->   
     <scala-maven-plugin.version>4.8.0</scala-maven-plugin.version>
@@ -422,13 +422,13 @@
         <version>${project.version}</version>
         <type>test-jar</type>
       </dependency>
-      <!-- #if scala-2.13 -->
+      <!-- #if scala-2.13 --><!--
       <dependency>
         <groupId>org.scala-lang.modules</groupId>
         <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
         <version>1.0.4</version>
       </dependency>
-      <!-- #endif scala-2.13 -->
+      --><!-- #endif scala-2.13 -->
       <dependency>
         <groupId>com.twitter</groupId>
         <artifactId>chill_${scala.binary.version}</artifactId>
@@ -1073,7 +1073,7 @@
         <exclusions>
           <exclusion>
             <groupId>org.scala-lang.modules</groupId>
-            <artifactId>scala-xml_2.13</artifactId>
+            <artifactId>scala-xml_2.12</artifactId>
           </exclusion>
         </exclusions>
       </dependency>
@@ -2866,49 +2866,9 @@
               <arg>-feature</arg>
               <arg>-explaintypes</arg>
               <arg>-target:jvm-1.8</arg>
-              <arg>-Wconf:cat=deprecation:wv,any:e</arg>
-              <arg>-Wunused:imports</arg>
-              <!--
-                TODO(SPARK-33805): Undo the corresponding deprecated usage suppression rule after fixed
-              -->
-              <arg>-Wconf:cat=scaladoc:wv</arg>
-              <arg>-Wconf:cat=lint-multiarg-infix:wv</arg>
-              <arg>-Wconf:cat=other-nullary-override:wv</arg>
-              <arg>-Wconf:cat=other-match-analysis&amp;site=org.apache.spark.sql.catalyst.catalog.SessionCatalog.lookupFunction.catalogFunction:wv</arg>
-              <arg>-Wconf:cat=other-pure-statement&amp;site=org.apache.spark.streaming.util.FileBasedWriteAheadLog.readAll.readFile:wv</arg>
-              <arg>-Wconf:cat=other-pure-statement&amp;site=org.apache.spark.scheduler.OutputCommitCoordinatorSuite.&lt;local OutputCommitCoordinatorSuite&gt;.futureAction:wv</arg>
-              <!--
-                SPARK-33775 Suppress compilation warnings that contain the following contents.
-                TODO(SPARK-33805): Undo the corresponding deprecated usage suppression rule after fixed.
-              -->
-              <arg>-Wconf:msg=^(?=.*?method|value|type|object|trait|inheritance)(?=.*?deprecated)(?=.*?since 2.13).+$:s</arg>
-              <arg>-Wconf:msg=^(?=.*?Widening conversion from)(?=.*?is deprecated because it loses precision).+$:s</arg>
-              <arg>-Wconf:msg=Auto-application to \`\(\)\` is deprecated:s</arg>
-              <arg>-Wconf:msg=method with a single empty parameter list overrides method without any parameter list:s</arg>
-              <arg>-Wconf:msg=method without a parameter list overrides a method with a single empty one:s</arg>
-              <!--
-                SPARK-35574 Prevent the recurrence of compilation warnings related to
-                `procedure syntax is deprecated`
-              -->
-              <arg>-Wconf:cat=deprecation&amp;msg=procedure syntax is deprecated:e</arg>
-              <!--
-                SPARK-35496 Upgrade Scala to 2.13.7 and suppress:
-                1. `The outer reference in this type test cannot be checked at run time`
-                2. `the type test for pattern TypeA cannot be checked at runtime because it
-                  has type parameters eliminated by erasure`
-                3. `abstract type TypeA in type pattern Seq[TypeA] (the underlying of
-                Seq[TypeA]) is unchecked since it is eliminated by erasure`
-                4. `fruitless type test: a value of TypeA cannot also be a TypeB`
-              -->
-              <arg>-Wconf:cat=unchecked&amp;msg=outer reference:s</arg>
-              <arg>-Wconf:cat=unchecked&amp;msg=eliminated by erasure:s</arg>
-              <arg>-Wconf:msg=^(?=.*?a value of type)(?=.*?cannot also be).+$:s</arg>
-              <!--
-                TODO(SPARK-43850): Remove the following suppression rules and remove `import scala.language.higherKinds`
-                from the corresponding files when Scala 2.12 is no longer supported.
-              -->
-              <arg>-Wconf:cat=unused-imports&amp;src=org\/apache\/spark\/graphx\/impl\/VertexPartitionBase.scala:s</arg>
-              <arg>-Wconf:cat=unused-imports&amp;src=org\/apache\/spark\/graphx\/impl\/VertexPartitionBaseOps.scala:s</arg>
+              <arg>-Xfatal-warnings</arg>
+              <arg>-Ywarn-unused:imports</arg>
+              <arg>-P:silencer:globalFilters=.*deprecated.*</arg>
             </args>
             <jvmArgs>
               <jvmArg>-Xss128m</jvmArg>
@@ -2924,6 +2884,13 @@
               <javacArg>${java.version}</javacArg>
               <javacArg>-Xlint:all,-serial,-path,-try</javacArg>
             </javacArgs>
+            <compilerPlugins>
+              <compilerPlugin>
+                <groupId>com.github.ghik</groupId>
+                <artifactId>silencer-plugin_${scala.version}</artifactId>
+                <version>1.7.10</version>
+              </compilerPlugin>
+            </compilerPlugins>
           </configuration>
         </plugin>
         <plugin>
@@ -3574,13 +3541,6 @@
       </properties>
     </profile>
 
-    <profile>
-      <id>scala-2.13</id>
-      <properties>
-        <scala.version>2.13.8</scala.version>
-      </properties>
-    </profile>
-
     <profile>
       <id>scala-2.12</id>
       <properties>
@@ -3590,6 +3550,20 @@
         -->
         <scala.version>2.12.17</scala.version>
       </properties>
+      <build>
+        <pluginManagement>
+          <plugins>
+          </plugins>
+        </pluginManagement>
+      </build>
+    </profile>
+
+    <profile>
+      <id>scala-2.13</id>
+      <properties>
+        <scala.version>2.13.8</scala.version>
+        <scala.binary.version>2.13</scala.binary.version>
+      </properties>
       <build>
         <pluginManagement>
           <plugins>
@@ -3603,16 +3577,51 @@
                   <arg>-feature</arg>
                   <arg>-explaintypes</arg>
                   <arg>-target:jvm-1.8</arg>
-                  <arg>-Xfatal-warnings</arg>
-                  <arg>-Ywarn-unused:imports</arg>
-                  <arg>-P:silencer:globalFilters=.*deprecated.*</arg>
+                  <arg>-Wconf:cat=deprecation:wv,any:e</arg>
+                  <arg>-Wunused:imports</arg>
+                  <!--
+                    TODO(SPARK-33805): Undo the corresponding deprecated usage suppression rule after fixed
+                  -->
+                  <arg>-Wconf:cat=scaladoc:wv</arg>
+                  <arg>-Wconf:cat=lint-multiarg-infix:wv</arg>
+                  <arg>-Wconf:cat=other-nullary-override:wv</arg>
+                  <arg>-Wconf:cat=other-match-analysis&amp;site=org.apache.spark.sql.catalyst.catalog.SessionCatalog.lookupFunction.catalogFunction:wv</arg>
+                  <arg>-Wconf:cat=other-pure-statement&amp;site=org.apache.spark.streaming.util.FileBasedWriteAheadLog.readAll.readFile:wv</arg>
+                  <arg>-Wconf:cat=other-pure-statement&amp;site=org.apache.spark.scheduler.OutputCommitCoordinatorSuite.&lt;local OutputCommitCoordinatorSuite&gt;.futureAction:wv</arg>
+                  <!--
+                    SPARK-33775 Suppress compilation warnings that contain the following contents.
+                    TODO(SPARK-33805): Undo the corresponding deprecated usage suppression rule after fixed.
+                  -->
+                  <arg>-Wconf:msg=^(?=.*?method|value|type|object|trait|inheritance)(?=.*?deprecated)(?=.*?since 2.13).+$:s</arg>
+                  <arg>-Wconf:msg=^(?=.*?Widening conversion from)(?=.*?is deprecated because it loses precision).+$:s</arg>
+                  <arg>-Wconf:msg=Auto-application to \`\(\)\` is deprecated:s</arg>
+                  <arg>-Wconf:msg=method with a single empty parameter list overrides method without any parameter list:s</arg>
+                  <arg>-Wconf:msg=method without a parameter list overrides a method with a single empty one:s</arg>
+                  <!--
+                    SPARK-35574 Prevent the recurrence of compilation warnings related to
+                    `procedure syntax is deprecated`
+                  -->
+                  <arg>-Wconf:cat=deprecation&amp;msg=procedure syntax is deprecated:e</arg>
+                  <!--
+                    SPARK-35496 Upgrade Scala to 2.13.7 and suppress:
+                    1. `The outer reference in this type test cannot be checked at run time`
+                    2. `the type test for pattern TypeA cannot be checked at runtime because it
+                     has type parameters eliminated by erasure`
+                    3. `abstract type TypeA in type pattern Seq[TypeA] (the underlying of
+                    Seq[TypeA]) is unchecked since it is eliminated by erasure`
+                    4. `fruitless type test: a value of TypeA cannot also be a TypeB`
+                  -->
+                  <arg>-Wconf:cat=unchecked&amp;msg=outer reference:s</arg>
+                  <arg>-Wconf:cat=unchecked&amp;msg=eliminated by erasure:s</arg>
+                  <arg>-Wconf:msg=^(?=.*?a value of type)(?=.*?cannot also be).+$:s</arg>
+                  <!--
+                    TODO(SPARK-43850): Remove the following suppression rules and remove `import scala.language.higherKinds`
+                    from the corresponding files when Scala 2.12 is no longer supported.
+                  -->
+                  <arg>-Wconf:cat=unused-imports&amp;src=org\/apache\/spark\/graphx\/impl\/VertexPartitionBase.scala:s</arg>
+                  <arg>-Wconf:cat=unused-imports&amp;src=org\/apache\/spark\/graphx\/impl\/VertexPartitionBaseOps.scala:s</arg>
                 </args>
                 <compilerPlugins combine.self="override">
-                  <compilerPlugin>
-                    <groupId>com.github.ghik</groupId>
-                    <artifactId>silencer-plugin_${scala.version}</artifactId>
-                    <version>1.7.10</version>
-                  </compilerPlugin>
                 </compilerPlugins>
               </configuration>
             </plugin>
diff --git a/repl/pom.xml b/repl/pom.xml
index 74ac775100cb..8c0f9f989c17 100644
--- a/repl/pom.xml
+++ b/repl/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-repl_2.13</artifactId>
+  <artifactId>spark-repl_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project REPL</name>
   <url>https://spark.apache.org/</url>
diff --git a/resource-managers/kubernetes/core/pom.xml b/resource-managers/kubernetes/core/pom.xml
index 72c7f1f12f42..9dab5496184e 100644
--- a/resource-managers/kubernetes/core/pom.xml
+++ b/resource-managers/kubernetes/core/pom.xml
@@ -19,12 +19,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-kubernetes_2.13</artifactId>
+  <artifactId>spark-kubernetes_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Kubernetes</name>
   <properties>
diff --git a/resource-managers/kubernetes/integration-tests/pom.xml b/resource-managers/kubernetes/integration-tests/pom.xml
index 3e25e7053707..02894f82eec9 100644
--- a/resource-managers/kubernetes/integration-tests/pom.xml
+++ b/resource-managers/kubernetes/integration-tests/pom.xml
@@ -19,12 +19,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-kubernetes-integration-tests_2.13</artifactId>
+  <artifactId>spark-kubernetes-integration-tests_2.12</artifactId>
   <properties>
     <sbt.project.name>kubernetes-integration-tests</sbt.project.name>
 
diff --git a/resource-managers/mesos/pom.xml b/resource-managers/mesos/pom.xml
index 267d6c7d84f2..7510ecac3e7f 100644
--- a/resource-managers/mesos/pom.xml
+++ b/resource-managers/mesos/pom.xml
@@ -19,12 +19,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-mesos_2.13</artifactId>
+  <artifactId>spark-mesos_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Mesos</name>
   <properties>
diff --git a/resource-managers/yarn/pom.xml b/resource-managers/yarn/pom.xml
index 2cda552a9c47..dcc7bcdd1af3 100644
--- a/resource-managers/yarn/pom.xml
+++ b/resource-managers/yarn/pom.xml
@@ -19,12 +19,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-yarn_2.13</artifactId>
+  <artifactId>spark-yarn_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project YARN</name>
   <properties>
diff --git a/sql/catalyst/pom.xml b/sql/catalyst/pom.xml
index cf01c0af4a45..9057cc8a20ef 100644
--- a/sql/catalyst/pom.xml
+++ b/sql/catalyst/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-catalyst_2.13</artifactId>
+  <artifactId>spark-catalyst_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Catalyst</name>
   <url>https://spark.apache.org/</url>
@@ -87,12 +87,12 @@
       <artifactId>spark-sketch_${scala.binary.version}</artifactId>
       <version>${project.version}</version>
     </dependency>
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
     <dependency>
       <groupId>org.scalacheck</groupId>
       <artifactId>scalacheck_${scala.binary.version}</artifactId>
diff --git a/sql/core/pom.xml b/sql/core/pom.xml
index 5d4f7572d002..7f4c2a4cfa54 100644
--- a/sql/core/pom.xml
+++ b/sql/core/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-sql_2.13</artifactId>
+  <artifactId>spark-sql_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project SQL</name>
   <url>https://spark.apache.org/</url>
@@ -89,12 +89,12 @@
       <scope>test</scope>
     </dependency>
 
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
     <dependency>
       <groupId>org.apache.orc</groupId>
       <artifactId>orc-core</artifactId>
diff --git a/sql/hive-thriftserver/pom.xml b/sql/hive-thriftserver/pom.xml
index 4bbb92d1376a..ad7fc0d2ac4b 100644
--- a/sql/hive-thriftserver/pom.xml
+++ b/sql/hive-thriftserver/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-hive-thriftserver_2.13</artifactId>
+  <artifactId>spark-hive-thriftserver_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Hive Thrift Server</name>
   <url>https://spark.apache.org/</url>
@@ -61,12 +61,12 @@
       <type>test-jar</type>
       <scope>test</scope>
     </dependency>
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
     <dependency>
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
diff --git a/sql/hive/pom.xml b/sql/hive/pom.xml
index b267830a3ad5..16d915c233ee 100644
--- a/sql/hive/pom.xml
+++ b/sql/hive/pom.xml
@@ -21,12 +21,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-hive_2.13</artifactId>
+  <artifactId>spark-hive_2.12</artifactId>
   <packaging>jar</packaging>
   <name>Spark Project Hive</name>
   <url>https://spark.apache.org/</url>
@@ -79,12 +79,12 @@
       <type>test-jar</type>
       <scope>test</scope>
     </dependency>
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
     <dependency>
       <groupId>${hive.group}</groupId>
       <artifactId>hive-common</artifactId>
diff --git a/streaming/pom.xml b/streaming/pom.xml
index a36370a1e8b6..bebfd3abcce3 100644
--- a/streaming/pom.xml
+++ b/streaming/pom.xml
@@ -20,12 +20,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-streaming_2.13</artifactId>
+  <artifactId>spark-streaming_2.12</artifactId>
   <properties>
     <sbt.project.name>streaming</sbt.project.name>
   </properties>
@@ -50,12 +50,12 @@
       <groupId>org.apache.spark</groupId>
       <artifactId>spark-tags_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #if scala-2.13 -->
+    <!-- #if scala-2.13 --><!--
     <dependency>
       <groupId>org.scala-lang.modules</groupId>
       <artifactId>scala-parallel-collections_${scala.binary.version}</artifactId>
     </dependency>
-    <!-- #endif scala-2.13 -->
+    --><!-- #endif scala-2.13 -->
 
     <!--
       This spark-tags test-dep is needed even though it isn't used in this module, otherwise testing-cmds that exclude
diff --git a/tools/pom.xml b/tools/pom.xml
index 9a088e84bc01..9dc136d42687 100644
--- a/tools/pom.xml
+++ b/tools/pom.xml
@@ -19,12 +19,12 @@
   <modelVersion>4.0.0</modelVersion>
   <parent>
     <groupId>org.apache.spark</groupId>
-    <artifactId>spark-parent_2.13</artifactId>
+    <artifactId>spark-parent_2.12</artifactId>
     <version>3.5.0-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>spark-tools_2.13</artifactId>
+  <artifactId>spark-tools_2.12</artifactId>
   <properties>
     <sbt.project.name>tools</sbt.project.name>
   </properties>