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Steps to reproduce the issue

Install Joomla4 via upgrade from 3.10 PHP 8 or 7.4 (installing on a subdomain)
Go to Global Configuration and make any change. My first experience was when I tried to change the editor to JCE. After several attempts, I tried to make and save a change (Hide Author Meta Data) to Global Configuration without any extensions (e.g., JCE, Akeeba...) and save the config file. Once the save button was pressed a login screen appeared and did not allow me to logon. I tried to change the password via PHPmyadmin, but that did not work.

Expected result

Save the file without exiting

Actual result

Logs out and cannot login. I can load extensions and work with extensions successfully, but if I touch Global Configuration after the install I lose the system

System information (as much as possible)

Joomla 4 Upgraded from 3.10 tried with both PHP 8 and then 7.4
I have it installed on a subdomain.

Additional comments

Could someone tell me how to fix this. I have been trying to figure this out for two days.