I had the same problem, nobody seems to have offered a reason or solution to this today yet. I can add a new event in my google calendar and it then appears on my synced iphone and also appears in Thunderbird on my mac. But only the events i add today are seen. I'm hoping this is not an issue with google, I paid for two programs yesterday (first was a pile of crap) to sync my google calendar with outlook after good old google turned off their sync system. But everything has been working fine on Tbird on my Imac until today.

I also tried re installing Thunderbird 31.1.2. Also both the latest releases were released before this issue started happening. It was just on Oct 9th that I have the issue and both were released much before that.

Now I am able to get it to sync with my google calendar if I have the "provider for google calendar" enabled (it has always been enabled) I can enter events etc and they are synced with Google calendar. As soon as I disable that add on then I can no longer create new events on Lightning not to mention all my original events are no longer showing up. Thank goodness they are still on my Google calendar but they wont sync back to Lightning. I currently have that add on disabled as I don't want to loose everything if it syncs to the blank calendar.

I also have google provider plugin activated as default. I can add and remove events but only when added today in to any part of my calendar, events written prior to today exist in my google calendar online but will not appear in my thunderbird/lightning calendar. This is a major issue for my work

Well my confidence is not recovered yet but here is what I did and now it seems to work. I exported my google calendar as an .ics file and then in Lightning went to the menu and "events and tasks" and imported the .ics file. All my events that had previously been created in Lightning and then synced to google now appear again in the Lightning calendar. I enabled the the google provider plug in again and it seems to sync back and forth. I have no clue why it happened in the first place and am hoping it doesn't happen again.

I think there is an issue with a recent update so before I re-import everything again and risk duplicating everything I am hoping someone will offer a more straight forward solution. Nothing was done to cause this my end, it just ....happened, it's a bit scary when in my case I have peoples wedding appointments for the next year with details in my calendar and all of a sudden they are all gone !! luckily I have everything on google and my phone and also synced to my PC in outlook. But the imac is my main working computer from which everything is run for my business, not having it reliable is a major setback.

I give up!!! Now it is not working properly. I think I will wait to see also if someone can fix the issue. I also did nothing on my end to cause this.

Yes come on people surely after 24hours of these queries appearing someone must have an idea about why it has happened.

I haven't used my laptop in a week. Logged on today and accepted the Thunderbird update finally.

I used Lightning and Provider for Google Calendar. I have years worth of data that I refer to in my Google calendar, but suddenly the only thing I see in Thunderbird Lightning are entries for the past month and the upcoming week -- and even this isn't complete. I don't see any logic to what appears and what doesn't. Just checked my Android phone and Google account online. They still contain my data, so I immediately backed up my (hopefully still complete) calendar info from Google.

I don't know what to do. I need this info for work and taxes. Please get this fixed ASAP!

Unfortunately, I am going to have to revert to using my Google calendar. I just don't have confidence in Lighting. Right now I can add an event and it will sync with my Google calendar and android phone but then those events on the lightning calendar seem to randomly disappear. Last week I believe those same events were on all calendars but now they are still on my Google calendar but not on my Lightning calendar which I do like to use. This random "deleting" makes it hard to test as it seems to work and then later those events are gone.

I recognize this is "open source" software and perhaps I should have contributed.  Kind of hard to do so now.

After more research, the problem may be in the Google provider. Go here for more info: https://groups.google.com/forum/#!forum/provider-for-google-calendar

I had the same problem, all entries disappeared and i couldn't install google calendar again. After deactivating "provider for google calendar* and installing google via CalDav i got my entries back but still no option to view my calendar. It just showed the upcoming events. By chance a saw the tabs on the top of the right side. Clicking to them brought my calendar back. No idea if sync and so works.

OK, this has worked for me : I've just removed lightning and provider. downloaded the latest lightning again, and version 0.32 of provider, installed lightning restarted, then install from file, provider and restarted, right click in left hand column of calendar to add new calendar- from network, follow instructions for google calendar, got the xml location address from my google settings. And finally I have my calendar back. everything has synced. Time will tell if it is still there in a day or so but for now it seems to work. Important note: Make sure you check "do not update" in the provider settings. today my calendar disappeared again, and I realized Provider had updated to 1.01 again. I deleted the calendar and reinstalled 0.32 and it reappeared.

I am having the same problem as bigdaymartin & KeithKlos. My office calendar was lost on or around the 9th of October after the last update. I have tried all the steps bigdaymartin provided on 10/15/14 with no luck! I am able to sign in to my gmail calendar and make changes but those changes are not reflected on my mozilla calendar even when I add new items. I have removed and added the apps multiple times with no luck. When I click on the calendar tab it says the office calendar is there with a check mark but no mirroring any information. This happened last year when an update took place and I can't remember how we got it back. I have noticed that the add on for lightening is showing version 2.6.6 but I have read about 3.1.1, not sure why it won't download that version. Any suggestions before I loss all my hair;)

Jeffries it would be better if you start your own thread and not spam all the people in this one by adding your problem. These people have an issue with Google calendar and the add on Provider. This does not sound like your problem.

In the mean time you need to have the correct version of Lightning to match the version of Thunderbird that you have. You can get the correct version here. https://addons.mozilla.org/en-US/thunderbird/addon/lightning/?src=hp-dl-mostpopular

Click View Other Version to see what goes with your version of Thunderbird.

All I know is that I removed/deleted both lightening and google provider and restarted thunderbird. Make sure that there is no longer a calendar entry on the left. install lightening, then install provider 0.32 when it's installed go in to the settings and untick the auto update. Then go and create a new calendar and click the option for via network and click on the google option, fill int eh address as given on your google account. This is how i got my calendar back and it's been working perfectly ever since.