@A Former User said in How can I re-enable a blacklisted extension?:
Secure Preferences
Thank you! If you can't find it in Preferences then check Secure Preferences. I was able to find it in Secure Preferences and it worked perfectly for me. Also you can install the Tapermonkey Beta extension since that's not blacklisted. Only difference is there are some bugs on the BETA version. I have no idea why opera has blacklisted this but it was a serious pain in the ass that I hope they fix. Doubt they ever will but that's what we have forums for 