Howard Miller

"I was using this template url: https://mymoodle.com/webservice/pluginfile.php/{contextid}/calendar/event_description/{itemid}/myimage.png?token={mytoken};"

That doesn't look like any web service call I would recognise. Where did you find the information to suggest that would work?

The last option. Although, it begs the question why, if you had a full backup, you didn't do a conventional migration ("without going into details).

It's probably *possible* to script something to match up the users and update that field in the database (it's just one table), it'll be hassle. If you're asking, I assume you don't have anybody to hand who could write a short script to do that.

4.1

 

...although, you should probably be fixing the problem that's stopping you running MySQL 8.x.   MySQL 5.7 became end of life in Oct 2023. This is not a great situation to be in. 

Yeh - you may need to migrate the site somewhere you CAN do the upgrade and then migrate it back again. Not ideal but that might be your only choice if your serer admins are intransigent.

Did it give a location for that error?

Regardless, enabling Debugging is Visvanath says, is your next step.