I can’t get into the admin panel

I can’t get into the admin panel; when I try to log in, the page reloads and again prompts me to enter my username/password, and so on in a circle.

If there is no message like “The username or password you entered is incorrect.”, then this behaviour is usually a sign that the sessions don’t work correctly on your server.

What actions can I take? support on the server offers only one option - to restore the old backup, but this option does not work. I tried doing a clean installation of modx, then importing the database and site files, logging in as a different user, and it worked, although the problem reappeared after a while. Is there a way to identify the problem more accurately?

How long is “a while”?

Maybe you could check the database table modx_session (and empty it, if it’s too big).

There are also MODX system settings related to sessions (like session_handler_class or session_gc_maxlifetime) that you could adjust.
(If you change the values directly in the database table modx_system_settings, make sure to clear the cache folder (core/cache) afterwards.)

The problem appeared after a few minutes of working in the admin panel.

My table modx_session is completely empty, there is not a single record.