If you want the english Version of Lightning, type into a Terminal:
sudo apt update
sudo apt install xul-ext-lightning
If you want a localized Version of Lightning, at the Moment, you cannot use the normal Add-On-Search in Thunderbird (incompatible).
Download manually the latest Beta-Version of Lightining for your System- and Language-Version from: https://archive.mozilla.org/pub/calendar/lightning/candidates/
Open Thunderbird > Add-Ons > Extensions > (Remove unwanted english Version of Lightining) >
> At the top of the page, click the Gear-Wheel-Button next to the Search-Box to open a menu
> Install Add-on From File
> Select Download-Folder and the .xpi-File > Install
=> All your Calendar-Data should be back
You can find Workarounds here: /bugs.launchpad .net/ubuntu/ +source/ thunderbird/ +bug/1797945)
(https:/
If you want the english Version of Lightning, type into a Terminal:
sudo apt update
sudo apt install xul-ext-lightning
If you want a localized Version of Lightning, at the Moment, you cannot use the normal Add-On-Search in Thunderbird (incompatible). /archive. mozilla. org/pub/ calendar/ lightning/ candidates/
Download manually the latest Beta-Version of Lightining for your System- and Language-Version from:
https:/
Open Thunderbird > Add-Ons > Extensions > (Remove unwanted english Version of Lightining) >
> At the top of the page, click the Gear-Wheel-Button next to the Search-Box to open a menu
> Install Add-on From File
> Select Download-Folder and the .xpi-File > Install
=> All your Calendar-Data should be back