Thunderbird 60 and extensions support

Thunderbird 60 will be the next major release of the desktop email program. It is a major release because Thunderbird is moved to a new Extended Support Release base (and as is Firefox when version 60 hits).
Thunderbird 60 comes with a refreshed user interface and plenty of other changes. Thunderbird users who run extensions in the email client may face compatibility issues as Thunderbird uses a strict compatibility policy when it comes to extensions.
In plain English: any extension that is not explicitly compatible with Thunderbird 60 will be disabled. Attempts to install incompatible Thunderbird extensions are blocked and users get the "could not be installed because it is not compatible with Thunderbird" error message.
The change is disastrous for Thunderbird's extension ecosystem. If you check the first two pages of extensions that have the most users on the Thunderbird Add-ons site, you will find out that only eight of the 40 Thunderbird extensions with the most users are compatible at this point in time.
The situation is even worse for the top 40 add-ons with the highest ratings as only five of them are compatible with Thunderbird 60.
Tip: you can verify if your Thunderbird extensions are compatible by visiting the Add-ons site and searching for the extensions.
There is a way out, however, at this point in time. The Thunderbird development team added an option to opt-out of the strict extension compatible checking enforcement. While that does not necessarily mean that extensions will work if they are not listed as compatible, chance is good that they do if they have been updated recently.
Here is what you need to do to flip the switch and disable strict extension version checking in the email client:
- Open Thunderbird if it is not open already.
- Tap on the Alt-key to display the menubar and select Tools > Options from the menu. Alternative: click on the new menu icon (the three horizontal bars) and select options when it opens.
- Switch to the Advanced tab.
- Click on the Config Editor button under General (it opens by default).
- Confirm that you will be careful.
- Search for extensions.strictCompatibility.
- Double-click on the preference.
A value of true (default) blocks extensions that are not explicitly listed as compatible with Thunderbird 60, a value of false disables the strict checking.
Thunderbird 60 is available as a beta version at the time of writing. You could install it on another machine or a virtual machine to test extensions that you require. The new version of the email client will be released on May 15, 2018 to the stable channel. Thunderbird 60 will be released a week after Firefox 60 which Mozilla plans to release on May 9, 2018.


You said that Outlook isn’t your main email client, so which is your main one?
I think its thunderbird
It is Mozilla Thunderbird.
Awesome! This actually solved my problem… what a stupid bug.
If this is the same bug that I’ve encountered, there may be another fix: (1) hover over open Outlook item in Taskbar, cursor up to hover over Outlook window item, and right-click; (2) this should give you Restore / Move / Size / Minimize / Maximize — choose Move or Size; (3) use your cursor keys, going arbitrarily N/S/E/W, to try to move or size the Outlook window back into view. Basically, the app behaves as though it were open in a 0x0 window, or at a location that’s offscreen, and this will frequently work to resize and/or move the window. Don’t forget to close while resized/moved, so that Outlook remembers the size/position for next time.
THANK YOU Claude!!! I could get the main window to launch but could not get any other message window to show on the desktop. You are my hero!!!!
Solved my issue! 6 years later and this is still problem…
Fantastic. Thank you. Size did the trick.
This solved my Outlook problem, too. Thank you. :)
Thank you so much, this started happening to me today and was causing big problems. You are a life saver, I hope I can help you in some way some day.
You are a god – thank you!
thanks a lot…. work like charm.. :-)
Yah…thanks Claude. I’ve been having the same problem and tried all the suggestions…your solution was the answer. It had resized itself to a 0/0 box. Cheers
Excellent post. This had me baffled even trying to accurately describe the problem. This fixed it for me.
Thank you
Thanks a lot for the article. Don’t know why it happenend, don’t know how it got fixed, but it was really annoying and now it works :-)
Thanks a lot. I was facing this issue from past 3 week. I tried everything but no resolution. The issue was happening intermittently and mainly when I was changing the display of screen ( as i use 2 monitors). The only option i had was to do system restore. But thanks to you.
I’ve been tried to sole this problem for 12hours. Your comment about changing the display of screen helped me a lot!! Thanks!!
Thank you…don’t know why this happened but your instructions helped me fix it. Running Windows 10 and office pro 2007
Great tip! Thanks!
Worked for me, too – thank you!!!
It’s Worked for me, too
thank you very much!
I had a similar issue with Outlook 2013 on Windows 10 and this helped me to fix it. Thank you very much!
Thank you so much. Solved!
Considering you published this in 2012, incredible not been debugged by Microsoft.
Thank you again. M
This problem was faced by only one user logging to TS 2008 r2 using outlook 2010.The issue was resolved.
Thanks.
Great tip. Thank you!!!! If it helps, I had to use the Control Key and the arrow keys at the same time to bring my window back into view. Worked like a charm.
Thank you, this worked !!!!
Man, you are a fucking god. Thanks a lot, what an annoying bug!!
Awesome, this post solved the issue. Many thanks!