Bugzilla

The background check also successfully re-enabled my add-on:

* Thunderbird was kept open the entire time
* Add-on manager showed the disabled add-on
* Background update fetched the new upper limit set in ATN and re-enabled it
* extensions.json was updated

I will now try to identify a code path, where this could go wrong. The place where the `extensions.json` file is saved is here:

https://searchfox.org/firefox-main/rev/0b21972a78f8915f73ce5579eeee2aa8c9c7d67e/toolkit/mozapps/extensions/internal/XPIDatabase.sys.mjs#1812-1842

Asking affected users to look for warning messages regarding `Failed to save XPI database` could give a hint.

The trigger for the save is here:

https://searchfox.org/firefox-main/rev/0b21972a78f8915f73ce5579eeee2aa8c9c7d67e/toolkit/mozapps/extensions/internal/XPIDatabase.sys.mjs#721-749

I do not see how that can fail. Any ideas? As it stands now, these are the error cases I could imagine:

- Caching issues in our CDN: Request to ATN continue to get the old data, but that should resolve over time and eventually return the updated data. In my tests, it took about 2h to get the updated data.

- File system access error, when trying to save the updated database: Do affected users share a common environment? Maybe sandbox issues due to flatpack or snap installs?

- Background updates disabled? Manual updates should work however...

- Firewall issue? The requests to the update server are blocked. Monitoring the requests issued by Thunderbird using the developer tools (as shown in my screenshot), could also give hints.

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