diff --git a/UPGRADE.md b/UPGRADE.md
index 14da50446e5..343cc458472 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -1,3 +1,16 @@
+# Upgrade to 3.5
+
+## Deprecate methods for configuring no longer configurable features
+
+Since 3.0, lazy ghosts are enabled unconditionally, and so is rejecting ID
+collisions in the identity map.
+
+As a consequence, the following methods are deprecated and will be removed in 4.0:
+* `Doctrine\ORM\Configuration::setLazyGhostObjectEnabled()`
+* `Doctrine\ORM\Configuration::isLazyGhostObjectEnabled()`
+* `Doctrine\ORM\Configuration::setRejectIdCollisionInIdentityMap()`
+* `Doctrine\ORM\Configuration::isRejectIdCollisionInIdentityMapEnabled()`
+
 # Upgrade to 3.4
 
 ## Discriminator Map class duplicates
@@ -26,7 +39,7 @@ The class `Doctrine\ORM\Mapping\Driver\DatabaseDriver` is deprecated without rep
 
 Output walkers should implement the new `\Doctrine\ORM\Query\OutputWalker` interface and create
 `Doctrine\ORM\Query\Exec\SqlFinalizer` instances instead of `Doctrine\ORM\Query\Exec\AbstractSqlExecutor`s.
-The output walker must not base its workings on the query `firstResult`/`maxResult` values, so that the 
+The output walker must not base its workings on the query `firstResult`/`maxResult` values, so that the
 `SqlFinalizer` can be kept in the query cache and used regardless of the actual `firstResult`/`maxResult` values.
 Any operation dependent on `firstResult`/`maxResult` should take place within the `SqlFinalizer::createExecutor()`
 method. Details can be found at https://github.com/doctrine/orm/pull/11188.
@@ -137,7 +150,7 @@ WARNING: This was relaxed in ORM 3.2 when partial was re-allowed for array-hydra
   `Doctrine\ORM\Query::HINT_FORCE_PARTIAL_LOAD` are removed.
 - `Doctrine\ORM\EntityManager*::getPartialReference()` is removed.
 
-## BC BREAK: Enforce ArrayCollection Type on `\Doctrine\ORM\QueryBuilder::setParameters(ArrayCollection $parameters)` 
+## BC BREAK: Enforce ArrayCollection Type on `\Doctrine\ORM\QueryBuilder::setParameters(ArrayCollection $parameters)`
 
 The argument $parameters can no longer be a key=>value array. Only ArrayCollection types are allowed.
 
diff --git a/src/Configuration.php b/src/Configuration.php
index ca22d9bb760..953c9cd98dc 100644
--- a/src/Configuration.php
+++ b/src/Configuration.php
@@ -610,7 +610,7 @@ public function enableNativeLazyObjects(bool $nativeLazyObjects): void
     }
 
     /**
-     * To be deprecated in 3.1.0
+     * @deprecated lazy ghost objects are always enabled
      *
      * @return true
      */
@@ -619,7 +619,7 @@ public function isLazyGhostObjectEnabled(): bool
         return true;
     }
 
-    /** To be deprecated in 3.1.0 */
+    /** @deprecated lazy ghost objects cannot be disabled */
     public function setLazyGhostObjectEnabled(bool $flag): void
     {
         if (! $flag) {
@@ -630,7 +630,7 @@ public function setLazyGhostObjectEnabled(bool $flag): void
         }
     }
 
-    /** To be deprecated in 3.1.0 */
+    /** @deprecated rejecting ID collisions in the identity map cannot be disabled */
     public function setRejectIdCollisionInIdentityMap(bool $flag): void
     {
         if (! $flag) {
@@ -642,7 +642,7 @@ public function setRejectIdCollisionInIdentityMap(bool $flag): void
     }
 
     /**
-     * To be deprecated in 3.1.0
+     * @deprecated rejecting ID collisions in the identity map is always enabled
      *
      * @return true
      */