Whenever I attempt to install or activate an addon I get:
“Error Oops, something went wrong (error). Please try again.”
It's not a very infornative message, so how do I find out why I get this error, and how do I fix it?
This type of error notification introduced does not help to debug the errors.
In most cases these are php errors, so you need to examine your add-ons.
Thom - if “display_errors” is on, the PHP error will be in the ajax response and it is that notice that I've found usually causes the “Opps”. It could be many other things, but that's what I've noticed the most.