Error on the site, what's the problem?

Question

Drupal

Error on the site, what's the problem?

Answer 1

I forgot to cover up here:
See the PHP logs to understand what the error is. Enable showing all errors in PHP. Drupal probably has a developer mode that will spit out all the errors on the screen, and not just give 500 without information about the error.
Most likely something is wrong with the server settings, or some plugin has failed.