This article shows how to resolve the login redirect that can happen when WordPress’ update hasn’t finished properly. Normally this redirect will be due to incomplete database update. You will see this redirect in the browser: wp-admin/upgrade.php?_wp_http_referer=%2Fwp-admin%2F
When trying to log in to the back end of a WordPress site the login will redirect to wp-admin/upgrade.php?_wp_http_referer=%2Fwp-admin%2F address. There will be no errors shown either on the page or in the error log. The redirect will take you to a blank page.
1 – Using a file manager from your hosting control panel or an FTP client navigate to the wp-content folder. Inside of it find the plugins folder.
2 – Rename the plugins folder to old_plugins.
3 – Open up your WordPress site and go to the login page.
4 – You will now see the page that will say: Database Update Required.
5 – Click the Update WordPress Database button.
After it’s done, it will take you to the next screen. Make sure to not log in to the site yet, otherwise you might lose some of your plugin setting or all plugins will get disabled!
6 – Go back to the file manager and rename the plugins folder back to plugins.
All done. The issue should now be gone and you will be able to log in to your site again.