unusable with large numbers of events Rated 1 out of 5 stars

Following up some other previous comments, I'm obliged to rate this add-on very poorly due to the wrong design philosophy.
When syncing with a remote calendar the application loads all the events (1000, with no option to set less), but if TB is restarted the whole syncing process restarts.
This design choice is maybe not an issue when you have 2/3 calendars with a total of few hundreds events, but when your company is using google calendar events and you have dozens of colleagues all having 1000 events to share, it all becomes completely unusable.
On top of it, the syncing process is started without any user prompt, so TB is completely non responsive, making it worthless.

While I appreciate the overall idea behind, the implementation is so rotten that I can only wish in a major rework.


Before commenting on the design philosophy, maybe you should read the code to confirm that this is actually the design philosophy used. Quite unfair to leave this kind of comment based on a few observations in the UI.

On the first synchronization, the Provider for Google Calendar downloads all events from the remote calendar, in batches of 1000 (hence the number you are seeing). It is not clear how many events are in the calendar at this stage. Once this batch is through, the next one is started, which also displays as xxx of 1000. Admittedly, I could display this differently by not always showing xxx of 1000 but jumping to 1001 of 2000. There is an advanced option to change the batch size, but this is not necessary.

Once the initial synchronization is done, the synchronization token is saved locally and all future synchronizations are incremental: only changed events are downloaded. So, let me guess, this is exactly how synchronization software should work? Yes, I thought so.

That said, what is happening in your case is probably that the initial sync is not complete, hence the token is not saved on shutdown and next time you start up, it attempts to start over. Please give it some time.

Almost continious sync of calendar events ! Rated 1 out of 5 stars

following comment from h_metzger (https://addons.mozilla.org/en-us/thunderbird/addon/provider-for-google-calendar/reviews/749824/), I'm also experiencing a complete slowdown in thunderbird with this add-on. TB shows (in the status bar at the bottom of the window) a very very long and slow sync of ~thousand of calendar events and that process is continuously repeating every few minutes !.
Anybody has found a workaround for this problem !

There's a trick! Rated 5 out of 5 stars

This module works perfectly for me. When it doesn't, (nothing appearing in both Agenda and tasks from Google) there is a trick to do :
Close thunderbird
Go to your profile folder (usually it's there : C:\Users\YourUserFolder\AppData\Roaming\Thunderbird\Profiles\YourThunderbirdProfile.default).
In that profile folder, open the folder named "calendar-data", delete everything in it (cache.sqlite something and deleted.sqlite) except the "backup" folder.
Close the open folders.
Restart Thunderbird and everything should be working fine.

Works perfectly Rated 5 out of 5 stars

Of course, Google changes it's rules wihtout further notifications, so, it can happen once every 2 years, few buggs appears. But what...? I've been using this app for the last 3 years and it works great, I don't even think about that. All you have to do is to READ TH MANUAL and do your little home work...

I rve read many negative reports, due to inappropriate behaviour of users...

Thank you to creator!


This user has 2 previous reviews of this add-on.

Get the job done as advertised but does so very slowly. I mean VERY. Rated 1 out of 5 stars

The addon provides access to your Google calender(s). Setting it up is a breeze. No problems there. The issues, however, start after. Thunderbird reacts very slowly. At first I thought this is because of the initial synchronization of the calenders. But that wasn't it, sadly. Thunderbird, with this addon, becomes unusable.

Works Great Rated 5 out of 5 stars

Keeps my schedules synced and easier for me to modify ever changing events from desk. Thank you!

Don't install unless you have time to spare Rated 1 out of 5 stars

Must have installed this at some point in the past, started getting this annoying message every time I tried to start thunderbird that provider needed me to login to get data. Didn't even know what that meant but finally gave in and logged in. I have several calendars with thousands of events, and it is not bright enough to only sync future events, so now I'm sitting here unable to do anything in my email until it decides to sync everything. Tried to uninstall it and restarted thunderbird, that failed as when I started thunderbird again it started syncing right where it left off.

The full synchronization only happens once, afterwards all synchronizations will be incremental and therefore very quick. This is how it is meant to be, the Google Calendar API allows synchronizing changes made using a token that defines when the last change was made. There is no simple way to just retrieve changed events after a certain time point without eventually having to re-synchronize all events if you scroll to the past.

Very slow switching between months Rated 3 out of 5 stars

It takes quite a long time to go from one month to the next, during which time Thunderbird will not respond. Yes, it is fetching info from the Internet, but this fetch is much slower than most Web interactions, perhaps because it is doing it on a field-by-field basis.

Ideally, the code would be fixed by somehow working faster. If that is not possible:

1) Create a local cache larger than one month. For me, that would be one month in the past and 11 months past the current month into the future. But since peoples' needs are different, have it be configurarable.

2) Do it in the background so I can do something else in Tbird while I am waiting for the data to come.

3) The Cache would ideally allow me to view and edit my calendar offline, to be sync'ed later.

I will gladly contribute if performance is improved.

perfecto Rated 5 out of 5 stars

this is awesome, because many times i'm charing my phone and don't access to my app. this allow me to add to google without opening calendar and have reminders to my desktop

Rated 4 out of 5 stars

Can't change calendars name if receive invitation to accept event. There is no option to change name so it remains as 'Home calendar' and that type of events do not sync with Google.

Add a participant doesn't work Rated 4 out of 5 stars

Hi, I am a great fan of this add-on for several years !
But recently the "add a participant" doesn't work. Everything looks fine in Lightning, but there is no synchro with the Google Agenda. It's a function I use alot so it's very handicapping!
A bug in PforGA or a new change of Google ?

A bug in Lightning. Please downgrade to Lightning or wait for to be released.

Well it used to work. Rated 1 out of 5 stars

After a recent update my calendar and email became glitchy, slow and almost unusable. Every few minutes I would get the "bad script" popup. Finally had to remove this add-on and go with the caldav option. Not as easy but it's stable.

This is a known issue and will soon be fixed. In the meanwhile, please unsubscribe from the Birthdays calendar.

Used to work great -- too slow now; I gave up... Rated 1 out of 5 stars

I had been using this fine for several years.
Recently, Provider for Google Calendar caused Thunderbird to become slow and unresponsive.

Switched to CalDav (see Rendered TB Slow, Uninstalled Rated 3 out of 5 stars
by giftpilzchen on August 4, 2015)

I'd prefer to use the Provider as it's much better for integrating with multiple Google calendars. Maybe the performance problem will be resolved some day and I can use this once again.


No Longer communicating from Lightning to Google Calendar Rated 5 out of 5 stars

I love this add-on but since Lightning 4.0.2 (at least that's when I noticed it) You can create and event in lighting and it show on your calendar in lighting but it doesn't actually create the event in google calendar (if you go to the actual google calendar your event isn't there). However if you create and event in google calendar (actually in google calendar not Thunderbird) you can see it fine from Lightning. Please fix. Thank you in advance.

Bug with attendees since Lightning 4.0.2 Rated 5 out of 5 stars

Since Lightning 4.0.2 i can't invite attendees.
Event is ok but only on selected calendar, no attendee.
Thank you.

This user has a previous review of this add-on.

Buggy & Superfluous -- use iCal option Rated 1 out of 5 stars

The set up always got stuck after entering the name for the calendar. Clicking "Next" did nothing and no Google authentication window opened up.

In the end there is not need for the Add-On. Lightning has an iCal option and on Google Calendar you can get an iCal Location (green iCal button from settings).

That works without a problem -- so further Add-On needed.

wasn't working... now its fixed!!! THX Rated 5 out of 5 stars

Been a huge fan of TB for many years, but as many have posted here, I started having lots of issues and freezing since last year due to Google Calendar Provider addon. Tried many things for several months, resisting the idea to abandon TB. Was just about to give up to Outshitlook until I did what "giftpilzchen" posted a couple posts down on the post titled "Rendered TB Slow, Uninstalled on August 4, 2015" and reinstalled all the calendars manually. Works like new, seconds to start...
Sensei giftpilzchen, THANK YOU

works partially Rated 2 out of 5 stars

Used to be a big Thunderbird user. Now coming back and hoping things work the same. Unfortunately not. Provider works partially by syncing a few calendars in Google, but not my primary calendar. tried everything I could think of and did a search to find solutions but no luck. and don't have any more time to play with it. so, although definitely worth supporting this developer (if it worked), I'm moving on to find a tool that works easily. oh the joys of software..

Good idea but problematic Rated 2 out of 5 stars

I desinstall de add-on because the solution is 2 post later!!

"par giftpilzchen le August 4, 2015 "

It works very good now, compatble with the new version of bierdiesync, all what i need!

Good Idea, Extremely Buggy Rated 2 out of 5 stars

Very good extension IF it wasn't so buggy. I had to uninstall it as it slowed Thunderbird down dramatically.