diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 627dc4694357..121760e2d33e 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -132,56 +132,6 @@ jobs:
               comment_id: +COMMENT_ID,
             } );
 
-  upgrade_test:
-    name: Test plugin upgrades
-    runs-on: ubuntu-latest
-    needs: build
-    if: needs.build.outputs.any_plugins == 'true'
-    timeout-minutes: 10  # 2022-03-04: Successful runs seem to take about 3 minutes, but give some extra time for the downloads.
-    services:
-      db:
-        image: mariadb:latest
-        env:
-          MARIADB_ROOT_PASSWORD: wordpress
-        ports:
-          - 3306:3306
-        options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=5
-    container:
-      image: ghcr.io/automattic/jetpack-wordpress-dev:latest
-      env:
-        WP_DOMAIN: localhost
-        WP_ADMIN_USER: wordpress
-        WP_ADMIN_EMAIL: wordpress@example.com
-        WP_ADMIN_PASSWORD: wordpress
-        WP_TITLE: Hello World
-        MYSQL_HOST: db:3306
-        MYSQL_DATABASE: wordpress
-        MYSQL_USER: root
-        MYSQL_PASSWORD: wordpress
-        HOST_PORT: 80
-      ports:
-        - 80:80
-    steps:
-      - uses: actions/checkout@v3
-        with:
-          path: monorepo
-
-      - name: Download build artifact
-        uses: actions/download-artifact@v3
-        with:
-          name: jetpack-build
-      - name: Extract build archive
-        run: tar --xz -xvvf build.tar.xz
-
-      - name: Setup WordPress
-        run: monorepo/.github/files/test-plugin-update/setup.sh
-
-      - name: Prepare plugin zips
-        run: monorepo/.github/files/test-plugin-update/prepare-zips.sh
-
-      - name: Test upgrades
-        run: monorepo/.github/files/test-plugin-update/test.sh
-
   jetpack_beta:
     name: Create artifact for Jetpack Beta plugin
     runs-on: ubuntu-latest
diff --git a/.github/workflows/slack-workflow-failed.yml b/.github/workflows/slack-workflow-failed.yml
index a3d245ff25ff..3ebf5dce1901 100644
--- a/.github/workflows/slack-workflow-failed.yml
+++ b/.github/workflows/slack-workflow-failed.yml
@@ -8,6 +8,7 @@ on:
       - Build Docker
       - Tests
       - Gardening
+      - Post-Build
       - PR is up-to-date
     branches: [ 'trunk', 'prerelease', '*/branch-*' ]
 
@@ -24,75 +25,124 @@ jobs:
         run: |
           source .github/files/gh-funcs.sh
 
-          gh_set_output message "$(
-            jq -nc --slurpfile event "$GITHUB_EVENT_PATH" '$event[0] as $e | $e.workflow_run as $run | {
-              icon_emoji: ":github-rejected:",
-              text: "*\( $e.workflow.name ) failed on \( $run.head_branch )*\n<\( $run.html_url )|Run #\( $run.id )>",
-              blocks: [
-                {
-                  type: "section",
-                  text: {
-                    type: "mrkdwn",
-                    text: "*\( $e.workflow.name ) failed on \( $run.head_branch )*"
+          # If this is triggered off of another "workflow_run" workflow, it'll always see the head_branch as "trunk".
+          # In that case, we assume it's setting display_title to be like "NAME on BRANCH" and extract the branch from there.
+          if jq -e '.workflow_run.event == "workflow_run"' "$GITHUB_EVENT_PATH" &>/dev/null; then
+            TITLE=$(jq -r '.workflow_run.display_title' "$GITHUB_EVENT_PATH")
+            BRANCH=${TITLE##* on }
+            echo "branch=$BRANCH" >> "$GITHUB_OUTPUT"
+
+            gh_set_output message "$(
+              jq -nc --slurpfile event "$GITHUB_EVENT_PATH" --arg branch "$BRANCH" '$event[0] as $e | $e.workflow_run as $run | {
+                icon_emoji: ":github-rejected:",
+                text: "*\( $e.workflow.name ) failed on \( $branch )*\n<\( $run.html_url )|Run #\( $run.id )>",
+                blocks: [
+                  {
+                    type: "section",
+                    text: {
+                      type: "mrkdwn",
+                      text: "*\( $e.workflow.name ) failed on \( $branch )*"
+                    }
+                  },
+                  {
+                    type: "context",
+                    elements: [
+                      {
+                        type: "plain_text",
+                        text: "Duration: \( ( $run.updated_at | fromdateiso8601 ) - ( $run.run_started_at | fromdateiso8601 ) | strftime( "%H:%M:%S" ) )"
+                      }
+                    ]
+                  },
+                  {
+                    type: "actions",
+                    elements: [
+                      {
+                        type: "button",
+                        text: {
+                          type: "plain_text",
+                          text: "Run #\( $run.id )"
+                        },
+                        url: $run.html_url
+                      }
+                    ]
                   }
-                },
-                {
-                  type: "context",
-                  elements: [
-                    {
-                      type: "plain_text",
-                      text: "Commit: \( $run.head_commit.id[0:8] ) \( $run.head_commit.message | sub( "\n.*"; ""; "m" ) )",
-                      emoji: false
-                    },
-                    {
-                      type: "plain_text",
-                      text: "Author: \( $run.head_commit.author.name )",
-                      emoji: false
-                    },
-                    {
-                      type: "plain_text",
-                      text: "Duration: \( ( $run.updated_at | fromdateiso8601 ) - ( $run.run_started_at | fromdateiso8601 ) | strftime( "%H:%M:%S" ) )"
+                ]
+              }'
+            )"
+          else
+            BRANCH=$(jq -r '.workflow_run.head_branch' "$GITHUB_EVENT_PATH")
+            echo "branch=$BRANCH" >> "$GITHUB_OUTPUT"
+
+            gh_set_output message "$(
+              jq -nc --slurpfile event "$GITHUB_EVENT_PATH" '$event[0] as $e | $e.workflow_run as $run | {
+                icon_emoji: ":github-rejected:",
+                text: "*\( $e.workflow.name ) failed on \( $run.head_branch )*\n<\( $run.html_url )|Run #\( $run.id )>",
+                blocks: [
+                  {
+                    type: "section",
+                    text: {
+                      type: "mrkdwn",
+                      text: "*\( $e.workflow.name ) failed on \( $run.head_branch )*"
                     }
-                  ]
-                },
-                {
-                  type: "actions",
-                  elements: [
-                    {
-                      type: "button",
-                      text: {
+                  },
+                  {
+                    type: "context",
+                    elements: [
+                      {
                         type: "plain_text",
-                        text: "Run #\( $run.id )"
+                        text: "Commit: \( $run.head_commit.id[0:8] ) \( $run.head_commit.message | sub( "\n.*"; ""; "m" ) )",
+                        emoji: false
                       },
-                      url: $run.html_url
-                    },
-                    {
-                      type: "button",
-                      text: {
+                      {
                         type: "plain_text",
-                        text: "Commit"
+                        text: "Author: \( $run.head_commit.author.name )",
+                        emoji: false
                       },
-                      url: "\( $run.head_repository.html_url )/commit/\( $run.head_commit.id )"
-                    },
-                    (
-                      $run.head_commit.message | sub( "\n.*"; ""; "m" ) | match( " \\(#([0-9]+)\\)$" ).captures[0].string | {
+                      {
+                        type: "plain_text",
+                        text: "Duration: \( ( $run.updated_at | fromdateiso8601 ) - ( $run.run_started_at | fromdateiso8601 ) | strftime( "%H:%M:%S" ) )"
+                      }
+                    ]
+                  },
+                  {
+                    type: "actions",
+                    elements: [
+                      {
                         type: "button",
                         text: {
                           type: "plain_text",
-                          text: "PR #\(.)"
+                          text: "Run #\( $run.id )"
                         },
-                        url: "\( $run.head_repository.html_url )/pull/\(.)"
-                      }
-                    )
-                  ]
-                }
-              ]
-            }'
-          )"
+                        url: $run.html_url
+                      },
+                      {
+                        type: "button",
+                        text: {
+                          type: "plain_text",
+                          text: "Commit"
+                        },
+                        url: "\( $run.head_repository.html_url )/commit/\( $run.head_commit.id )"
+                      },
+                      (
+                        $run.head_commit.message | sub( "\n.*"; ""; "m" ) | match( " \\(#([0-9]+)\\)$" ).captures[0].string | {
+                          type: "button",
+                          text: {
+                            type: "plain_text",
+                            text: "PR #\(.)"
+                          },
+                          url: "\( $run.head_repository.html_url )/pull/\(.)"
+                        }
+                      )
+                    ]
+                  }
+                ]
+              }'
+            )"
+          fi
 
       - name: Send message to alerts channel
         uses: slackapi/slack-github-action@v1.23.0
-        if: github.event.workflow_run.head_branch == 'trunk'
+        if: steps.message.outputs.branch == 'trunk'
         with:
           channel-id: ${{ secrets.SLACK_JP_ALERTS_CHANNEL }}
           payload: ${{ steps.message.outputs.message }}
@@ -101,7 +151,7 @@ jobs:
 
       - name: Send message to releases channel
         uses: slackapi/slack-github-action@v1.23.0
-        if: contains( github.event.workflow_run.head_branch, '/branch-' ) || github.event.workflow_run.head_branch == 'prerelease'
+        if: contains( steps.message.outputs.branch, '/branch-' ) || steps.message.outputs.branch == 'prerelease'
         with:
           channel-id: ${{ secrets.SLACK_RELEASES_CHANNEL }}
           payload: ${{ steps.message.outputs.message }}