Rated 1 out of 5 stars

Same as the other users, after the 17 upgrade, I have lost all my calendar data and nothing is working...

This review is for a previous version of the add-on (1.9). 

Same as others, if you are using the Provider please upgrade it to 0.18. Also check if your anti virus software quarantined calbasecomps.dll and if so restore it or reinstall Lightning. If the problem persists please email mozilla@kewis.ch