Grrr they may call it a stable release but if it doesn't work with any extensions (or at least certainly MOST extensions that I can tell) they should be offering the 68.x installer on the download page for Thunderbird, rather than just the 78.x version. I'm in the process of setting up a new laptop and can't use any of the extensions I use on Thunderbird on my other machines all running 68.x with this new 78.x version. Sadly I didn't keep the installers of 68.x on my previous laptops to be able to install it that way. I don't want to be on a "Test Channel" as they put it. That should be an opt in thing made available along with the version that is still working with all the extensions. Not keen to download an old installer from non-Thunderbird sites - that's always risky.