Drupal errors

Drupal 7

After restoring a "backup migrate" backup from production server to test server, I had white screen with "500 Internal Server Error". The test server is on windows so I don't have drush, so I did some things in database manually. No idea whether all steps were necessary or only the last one, but I finally got it working.

First thing I did was clear cache tables. In phpmyadmin, check tables starting with "cache_" and choose operation "Empty" at the bottom of the screen. It didn't help.

Then I changed the system paths (public, private and temp) in database. Table "variable" contains three records: "file_private_path", "file_public_path" and "file_temporary_path". See here how to change them. It didn't help.

Then I noticed (in debugger) that Drupal was complaining about being unable to delete a record from table "semaphore", so I deleted it manually (a record, not the table). It didn't help.

And then finally I noticed that the error message is in debugger is "SQLSTATE[HY000]: General error: 2006 MySQL server has gone away" and it turned out that increasing max_allowed_packet in my.ini helped, as described in this blog.

By the way, next time I have such error I'll start with deleting lines from settings.php which prevent error display on screen (makes sense in production but not on test server) so perhaps the errors will be easier to find out without using debugger.