diff --git a/.github/workflows/reusable-upgrade-testing.yml b/.github/workflows/reusable-upgrade-testing.yml
index e4c60e6ffea9f..5a35fa70dc701 100644
--- a/.github/workflows/reusable-upgrade-testing.yml
+++ b/.github/workflows/reusable-upgrade-testing.yml
@@ -79,39 +79,63 @@ jobs:
           -c "exec docker-entrypoint.sh mysqld${{ inputs.db-type == 'mysql' && contains( fromJSON('["7.2", "7.3"]'), inputs.php ) && ' --default-authentication-plugin=mysql_native_password' || '' }}"
 
     steps:
+      - name: Compare versions
+        id: version_check
+        env:
+          OLD_VERSION: ${{ inputs.wp }}
+          NEW_VERSION: ${{ inputs.new-version }}
+        run: |
+          # Add .0 if version is X.Y format
+          [[ $OLD_VERSION =~ ^[0-9]+\.[0-9]+$ ]] && OLD_VERSION+=".0"
+          [[ $NEW_VERSION =~ ^[0-9]+\.[0-9]+$ ]] && NEW_VERSION+=".0"
+
+          if printf '%s\n%s\n' "$OLD_VERSION" "$NEW_VERSION" | sort -V -C; then
+            echo "valid=true" >> "$GITHUB_OUTPUT"
+          else
+            echo "valid=false" >> "$GITHUB_OUTPUT"
+          fi
+
       - name: Set up PHP ${{ inputs.php }}
         uses: shivammathur/setup-php@20529878ed81ef8e78ddf08b480401e6101a850f # v2.35.3
+        if: ${{ steps.version_check.outputs.valid == 'true' }}
         with:
           php-version: '${{ inputs.php }}'
           coverage: none
           tools: wp-cli
 
       - name: Download WordPress ${{ inputs.wp }}
+        if: ${{ steps.version_check.outputs.valid == 'true' }}
         run: wp core download --version="${WP_VERSION}"
         env:
           WP_VERSION: ${{ inputs.wp }}
 
       - name: Create wp-config.php file
+        if: ${{ steps.version_check.outputs.valid == 'true' }}
         run: wp config create --dbname=test_db --dbuser=root --dbpass=root --dbhost="127.0.0.1:${DB_PORT}"
         env:
           DB_PORT: ${{ job.services.database.ports['3306'] }}
 
       - name: Install WordPress
+        if: ${{ steps.version_check.outputs.valid == 'true' }}
         run: |
           wp core ${{ inputs.multisite && 'multisite-install' || 'install' }} \
           --url=http://localhost/ --title="Upgrade Test" --admin_user=admin \
           --admin_password=password --admin_email=me@example.org --skip-email
 
       - name: Pre-upgrade version check
+        if: ${{ steps.version_check.outputs.valid == 'true' }}
         run: wp core version
 
       - name: Update to the latest minor version
+        if: ${{ steps.version_check.outputs.valid == 'true' }}
         run: wp core update --minor
 
       - name: Update the database after the minor update
+        if: ${{ steps.version_check.outputs.valid == 'true' }}
         run: wp core update-db ${{ inputs.multisite && '--network' || '' }}
 
       - name: Post-upgrade version check after the minor update
+        if: ${{ steps.version_check.outputs.valid == 'true' }}
         run: wp core version
 
       - name: Download build artifact for the current branch
@@ -126,14 +150,16 @@ jobs:
           wp core update develop.zip
 
       - name: Upgrade to WordPress ${{ inputs.new-version }}
-        if: ${{ inputs.new-version != 'develop' }}
+        if: ${{ inputs.new-version != 'develop' && steps.version_check.outputs.valid == 'true' }}
         run: |
           wp core update ${{ 'latest' != inputs.new-version && '--version="${WP_VERSION}"' || '' }}
         env:
           WP_VERSION: ${{ inputs.new-version }}
 
       - name: Update the database
+        if: ${{ steps.version_check.outputs.valid == 'true' }}
         run: wp core update-db ${{ inputs.multisite && '--network' || '' }}
 
       - name: Post-upgrade version check
+        if: ${{ steps.version_check.outputs.valid == 'true' }}
         run: wp core version
diff --git a/.github/workflows/upgrade-testing.yml b/.github/workflows/upgrade-testing.yml
index fb1d973344c18..75355a41b3bcb 100644
--- a/.github/workflows/upgrade-testing.yml
+++ b/.github/workflows/upgrade-testing.yml
@@ -91,7 +91,7 @@ jobs:
       db-type: ${{ matrix.db-type }}
       db-version: ${{ matrix.db-version }}
       wp: ${{ matrix.wp }}
-      new-version: ${{ inputs.new-version && inputs.new-version || 'latest' }}
+      new-version: ${{ inputs.new-version && inputs.new-version || '6.6' }}
       multisite: ${{ matrix.multisite }}
 
   # Tests 6.x releases where the WordPress database version changed on the oldest and newest supported versions of PHP 7 & 8.