See here for a workaround: "How can I re-enable a blacklisted extension?".

At first, I wanted to re-enable Tampermonkey too. Now that I think about it, I wonder why it's been blacklisted. Who manages the blacklist, or is it automated? Either way, I did some digging, and it turns out that Tampermonkey has gone closed-source recently. This seems a bit alarming to me. I just hope that they aren't pulling a Stylish because there is no good alternative to this extension except for ViolentMonkey, which has a possibly questionable privacy policy. Nevertheless I have no real reason to suspect anything except for becoming closed-source and becoming blacklisted with no explanation, neither of which really prove anything.

@ViAik Thank you, this works (so far)! This let me back up my data so that I didn't lose it all.

As a note to other users, it might help to do this:

1. Find your profile by going to opera://about.

• For Windows, it is likely C:\Users [username]\AppData\Roaming.
• For macOS, it is likely /Users/[username]/Library/Application Support/com.operasoftware.Opera. You can access this folder by opening Finder then clicking "Go" in the menu bar, then "Go to Folder..." and pasting the profile location.

2. Make a backup of the Preferences file.
3. Open the Preferences file (use TextEdit on macOS) and paste its contents into an online JSON beautifier
4. Look for the blacklist settings in the lines below the extension ID. Also, for Mac users, the profile location is probably . In general, you can find your profile path by going to opera://about/.
5. Set "blacklist" to false instead of true, and set "blacklist_state" to 0.
6. Save the file. If something goes wrong, restore your backup.