Unfortunately, probably impossible, thunderbird is not backward compatible.
So in the add-on list are a lot of add-ons witch aren’t suitable for the actual version of thunderbird.
So why not make a filter to display only the add-ons who can be used by the actual thunderbird version? Maybe, there could be a filter to activate witch displays all the add-ons , as it does now. I wouldn’t use the the last option, but maybe there are people who need old add-ons.
The filter is there, but kind of hidden:
In the main page
https://addons.thunderbird.net/de/thunderbird/
click on the green arrow in the search field, then in the left pane click on “Any Thunderbird”, and then you can select the version you want.
Danke, it works fine now
I can’t find a way to get to this easily in the addons.thunderbird.net user interface, but if you go to this URL:
and then enter your search terms in the search box and hit enter or click the search button, the results will be limited to add-ons which are compatible with Thunderbird 78. You can edit what come after “appver” in the URL above to search for add-ons compatible with a different Thunderbird version.
Regards,
Jonathan Kamens
As [C-E] told, click on the green arrow… Was the solution for me.