Please edit the file core/classes/Email.php in a text editor. Delete all code inside, and replace with this new code: https://gist.githubusercontent.com/samerton/a26df55561f9735eb2f69af6868f57fb/raw/39600339f889e35546daa8a7f9b89788cfa73261/Email.php
Then send a test email in the StaffCP -> Configuration -> Emails tab, and a full debug log will appear on screen with more information.
Please see the "Broken API" section of this issue: https://github.com/NamelessMC/Nameless/issues/2446
Thank you for providing this translation @0spy !
Would we have your permission to include the translation in the next version of Nameless (the license the files are released under is MIT)
You will have to either restore from backup or run a MySQL query which you can build from piecing these parameters together: https://github.com/NamelessMC/Nameless/blob/v2.0.0-pr12/core/classes/Queries.php#L153
There should never be any need to remove a table from the database