remove lightning and reinstall it.

Thanks Matt. I found this thread because I had the same problem. Remove and Install through the Add-Ons tab fixed it.

That worked for me. For 1 or 2 machine restarts. Lightning isn't working for me again, even after re-trying that solution several times. I'm dumping Lightning and Thunderbird. I've used both for years and I'm really sorry to see it go. The Recurring Appointment tools were the best available.

I am puzzled by this. Lightning has worked just fine for me in 52.3.0 and continues to do so in 52.4.0.

I have the same problems and have not found a solution yet.

Have tried uninstall and reinstall extension, creating a new profile (where calendar works) and copy across the calendar files from new into old extension folder and also done a number of restarts. No luck.

The weird thing is I can still see Calendar and tasks menu items and icons but they do not do anything when clicked so are inoperable. Something prevents them from working. Another add-on, but which one as I did not add any recently.

Any clues?

This is getting confusing: I'm sure last time I updated, it was built into Thunderbird. Now (52.5.2) I have to reinstall it as an extension. But I am SO thankful it still works!

Lightning is an add on. Always has been. Adding Lightning to the Thunderbird download did not change that.

I have the same problem as Pete0762 above. I can see the icons to add events but they are inactive as his. All my previous events have gone.

I have tried to reinstall Lightning, but it won't install. When I first did it, it said to restart, but after restarting several times, it still showed restart - it never enabled. Now, after shutting down the computer a couple of times and restarting everything, Lightning in Addons just sits saying "Installing" for hours. My Provider for Google Calendar disappeared too, and I have the same problem trying to reinstall it. I have TB 52.5.2.