Extension installing or activation causes error

When I try to activate an extension the admin panel no longer loads. Instead I get an 'Something went wrong' message in the right panel.

php flarum migrate

and

php flarum cache:clear

don't change anything
Trying to install an extionsion via composer ends with the same result.
When removing the extension via

composer remvoe

the admin panel is working again.

achlys Do you have debug mode enabled? If not, enable it and see if you get any errors. Also, check errors in the javascript console if possible.