Problems with transferring my website to a new hosting

Hello everyone,

A problem occurred while transferring a small site to a new hosting. We did the process, but the admin panel hardly works

For example, when I try to edit an article, everything is fine.
But when I try to do something with the structure or users - then I receive 500 error. Server response time is too long though we increased the maximum to 300 seconds.

I think that the problem is definitely not with hosting, cause we already got two sites there. The hosting is gthost.com, maybe someone knows what can be wrong with drupal there.

Tried to clean the cache from the admin panel but also received 500 error.
Lately I cleaned it through MySQL but nothing changed
Site_domain / admin / reports / dblog also returnes 500

Please share your wisdom:)