Ticket #26173: 26173.diff

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

@@ -887 +887 @@
         $db_upgrade_url = admin_url('upgrade.php?step=upgrade_db');
         wp_remote_post($db_upgrade_url, array('timeout' => 60));
 
+        // Clear the cache to prevent an update_option() from saving a stale db_version to the cache
+        wp_cache_flush();
+
         // Remove working directory
         $wp_filesystem->delete($from, true);