Ticket #51686: 51686.2.diff

src/wp-admin/includes/update-core.php

@@ -946 +946 @@
         }
 
         $wp_filesystem->chmod( $versions_file, FS_CHMOD_FILE );
+
+        /*
+         * `wp_opcache_invalidate()` only exists in WordPress 5.5 or later,
+         * so don't run it when upgrading from older versions.
+         */
+        if ( function_exists( 'wp_opcache_invalidate' ) ) {
+                wp_opcache_invalidate( $versions_file );
+        }
+
         require WP_CONTENT_DIR . '/upgrade/version-current.php';
         $wp_filesystem->delete( $versions_file );
 
@@ -1117 +1126 @@
                         $result = new WP_Error( 'copy_failed_for_version_file', __( 'The update cannot be installed because we will be unable to copy some files. This is usually due to inconsistent file permissions.' ), 'wp-includes/version.php' );
                 }
                 $wp_filesystem->chmod( $to . 'wp-includes/version.php', FS_CHMOD_FILE );
+
+                /*
+                 * `wp_opcache_invalidate()` only exists in WordPress 5.5 or later,
+                 * so don't run it when upgrading from older versions.
+                 */
+                if ( function_exists( 'wp_opcache_invalidate' ) ) {
+                        wp_opcache_invalidate( $to . 'wp-includes/version.php' );
+                }
         }
 
         // Check to make sure everything copied correctly, ignoring the contents of wp-content.