Extensions are developed and supported by their independent authors. When upgrading releases, those authors sometimes require extra time to complete their addon upgrades. The thunderbird team keeps them aware of upcoming changes, but the authors control their own timeline. Thunderbird has always held the position that profiles are subject to changes when upgrading to new releases.

Hi team, I tried switching over to the monthly release branch however none of my addons work.

Please contact individual add-on authors with details. Thanks.

Is there some major incompatibility introduced (aka WebExtensions)? I can not find any documentation anywhere as to what changed or why an extension would not work with 129+.

I am not aware of anything specific between 129 and 136 that would force redownload of messages. Hence, there would not be anything documented.

Also the release notes do not mention that 136 changes the Profile format, requiring a redownload of all messages from the server and therefore reindexing. This took several hours, only to find the addons don't work. Downgrading Thunderbird gives a profile error, and requires the `--allow-downgrade`switch to restore functionality. There should be a warning in the release notes regarding the one-way nature of the upgrade.

FWIW, this has been the case since version 68 - https://support.mozilla.org/en-US/kb/dedicated-profile-thunderbird-installation

There is no direct answer to my question. Where there changes to the Addons API between 128 and 136 that would render plugins incompatible?

BTW I was upgrading from ESR which is currently v128. There are no release notes for 136 mentioning profile format changes. A document from version 68 is irrelevant.

Typical responses that do not actually consider the user impact.

First, we're volunteers here and your questions assume you're interacting with the highest levels in the organization. You're not. We're peers, just as you, offering tips where we know them. Developers usually set a max release level to what they feel sure will work. So, when a developer sets an addon for a max of 128, that does not mean it won't work with 128, it only means that 136 wasn't available when the addon was updated. You can experiment on your own, if you don't mind a bit of risk. the addon is actually a zip file. you can unzip it, open the manifest.json file and change the max number to whatever you wish, rezip and install and see if it works. I have done that many times with no problems with addons, but not 100%.

There is no direct answer to my question. Where there changes to the Addons API between 128 and 136 that would render plugins incompatible?

Mostly, no. But add-on authors must update their add-on in the add-ons center to state what versions are compatible - the Thunderbird team can't do that for them.

Which specific add-ons are a problem?