Hi there!

Thanks for reaching out.

Did you follow this while migrating your site, please?

https://www.joomshaper.com/blog/how-to-update-your-site-to-joomla-4

Which template are you using there?

More info about the error is here: https://forum.joomla.org/viewtopic.php?t=988008

And the following video guide may help too: https://youtu.be/ZO9nmdsLlFw?t=22

Best Regards

Hi, in general Joomla migration/upgrade is beyond JoomShaper support.

But to see what caused that problem edit your configuration.php file and set those:

Then check /administrator again.

Probably old plugin or module caused that problem. When you will know which one, just rename its folder name!