Oh btw this is Firefox for Linux v129.0.1 running on pop-os (Ubuntu fork) 22.04 LTS.

And the issue doesn't happen on my Windows PC.

You can try Firefox from the official Mozilla server if you currently use a version from the repositories of your Linux distribution to see if it behaves differently.

• https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

You can open the about:policies page to see if policies are active and if errors are reported.

• https://support.mozilla.org/en-US/kb/see-active-policies-firefox-enterprise

Release notes for 129.0.2:

• Fixed an issue with screen readers prompting "Alert" when hovering over tabs. (Bug 1908873)

• Fixed an issue where drag-and-drop operations would not work as expected with extensions that rely on this functionality. (Bug 1911486)

Seems highly unlikely that either of those are relevant.

As for policies, I'm not running Enterprise.

UPDATE: I just did apt upgrade to 192.0.2 and sure enough that didn't fix the bug, and furthermore the instructions on support.mozilla.org state that installing from my distribution package manager is Recommended.

Any common reasons for the behavior I'm observing?

Troubleshooting ideas?

More specifically, any ideas why the settings in extensions.json change for each of the recent add-ons after restart? Similar observations were noted and unresolved in October and I'm hoping I haven't run into the same dead end here.

You can check extensions.json in the Firefox profile folder to see if there is information about this file present.

• https://firefox-source-docs.mozilla.org/devtools-user/json_viewer/

You can use the button in "Help -> More Troubleshooting Information" (about:support) to go to the current Firefox profile folder or use the about:profiles page (Root directory).

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

I've unexpectedly stumbled into a solution as follows:

1. Include add-ons again in Sync settings
2. Create new profile
3. Log in to Firefox account and wait for everything to sync
4. Change default profile to the new one

At this point I noticed that my OneTab data was missing because it's stored locally in each individual profile folder. To find the old extension folder I had to open my old profile again.

Lo and behold my originally described issue with recently installed add-ons has resolved!

I set my default back to my original profile, deleted the new one, restarted Firefox, and miraculously it's still resolved.

I'm guessing it was Sync related and somehow creating the new profile stopped the syncGUID values in extensions.json from changing on every startup.

I'm happy it's resolved though wary that it could happen again and I always prefer to know the whys and not just the hows, so I welcome any ideas why this solved it.

Same issue here, i have to re-activated newly installed add-ons, after every browser restart. Tested with different add-ons from the official store.

Thanks for the work around @Lionel Holt, but i wait until the Firefox devs fixing this.

I hope it get fixed soon, because it is very annoying...

@Dark-Noir I understand although it's not too much effort to retain your sanity LOL plus it would be nice having confirmation that the solution is reproducible which would probably also help the devs fix the bug quicker. 🙂

Also I'm not expecting this to be fixed soon or possibly ever since apparently not many users are reporting it.

By the way, what is your operating system?