Support

> I have tried to disable the provider.php and that didn't work

If you have renamed that file Joomla cannot load the System - Admin Tools plugin anymore. Therefore your issue wouldn't be related to Admin Tools.

Do you have any third party security plugins such as Admin Exile? These plugins also implement their own secret URL parameter feature.

First, upgrade Admin Tools. "Current" is not a version number. Considering that we released a new version a few hours ago, after you filed your ticket, whichever version you are using is most definitely not current. So let's start with an update to make sure that you have not bumped into an issue we have already resolved.

Next up, we need to get your site to produce a detailed error message which will help us identify the problem. Go to your site's Global Configuration and set Error Reporting to Development and Site Debug to Yes. Now rename provider.php back to its previous name. Clear the cache if you need. You should now get a far more detailed error message. Copy and paste it here so I can tell what is going on.

If you got no error message and everything worked file — you had a problem we've fixed in the latest release, no further action necessary. Go back to Global Configuration; set Error Reporting to None and Debug Site to No.

If you have renamed the file plugins/system/admintools/service/provider.php (please double check) and you are still redirected to the homepage then your problem is not with Admin Tools.

If the file plugins/system/admintools/service/provider.php still exists, please rename it to plugins/system/admintools/service/provider.php.bak to regain access to your site's administrator. If this didn't help your problem is not with Admin Tools; stop reading.

Go to administrator, Components, Admin Tools for Joomla, Web Application Firewall, Configure WAF, delete the contents of the Secret URL Parameter setting as per https://www.akeeba.com/documentation/admin-tools-joomla/atwafissues.html