You can navigate to the settings.php file in /sites/default/settings.php .
Right after <?php opening tag.
$config['system.logging']['error_level'] = 'verbose';
Now if you come to the actual error, it will be printed out rather than hidden. Do not forget to drush cr if possible, because sometimes an error can be cached. (anyway, Drush will also tell you an error when trying to clear the cache)