Mautic 4.20 throws 500 internal error in asset and form page/tab

[mzagmajster]

Yes backup mauitc database (on mysql server) before you start any migration. I have written one answer how & why to go about errors during migration:

MySQL error upgrading to 4.2

Hi there, What version are you updating from here? You may have outstanding migrations if you have had incomplete updates in the past. Does it do anything if you check in the UI for the schema updates?

I would try something similar in your situation.