Infuriating: Working on Linux Mint, I regularly update my system. The last update included a Thunderbird update (60 -> 68), and an important plug-in stopped to work, the incredibly useful Quick Folder Move. After spending an hour on this, I decided to downgrade – of course some plugins that were updated in the meantime stopped to work.
It’s 2019: These problems should not exist any more, after the last big update that broke almost all plugins. It’s scary to say, but by now, I find Outlook more user-friendly than Thunderbird. For a long time it was the other way around. It’s so sad to see such an important project go to waste.