The website encountered an unexpected error. Please try again later.-- Upgrading Drupal from 8.9 to 9.3.5

Question

I am upgrading my drupal project from 8.9 to 9.3.5 but after the upgrade while hitting website one error occur i.e

The website encountered an unexpected error. Please try again later.

I followed the steps mentioned in the drupal site for upgrading drupal from 8 to 9 or (later) click here for steps but didn't work for me.

Will anyone please help me or provide proper steps to upgrade drupal from 8.9 to 9.3.5?

Answer 1

You should try to get more information about the error.

Add to your settings.php file:

$config['system.logging']['error_level'] = 'verbose';

and check the output on your screen again.

You may also try drush to take a look at selecting the option errors from the terminal.

drush watchdog:list

Answer 2

I've run into this same issue multiple times. If you haven't already done so, try going to /update.php multiple times. (It seems to clear out the update process junk/leftovers and let it work.)

Other than that, it's always some kind of file issue. (I still update manually due to my server setup.) Sometimes it was a folder/sub folder that didn't upload fully or other times it was that some module simply refused to work with the new upgrade until that was updated.