CalDAV calendar syncronises way too much, unusable with poor connection

eM Client seems to do a sync whenever you change view, change week, scroll, or do more or less anything. This is way too much and makes it very hard to use.

With a fast connection, this is annoying, but usable

  • The sync takes about 2-3s for me
  • During this time, you can’t read your calendar as it is redrawing
  • If you edit an event or dismiss a reminder during a sync, you get an error that the item has been removed from the calendar and lose your changes.

If you have a poor connection, sync takes forever. If you are charged for bandwidth, emClient would waste tons of $$.

Should only sync max every 5 minutes or so, perhaps even less. Try to do it in the background - NOT immediately after user input, when for sure the user will not want the disturbance. Also try to make it less visually and functionally disruptive, so I can continue to work during a sync - particularly in the 99% case where nothing has changed on the server.


that first question - it is intended to be synchronized instantly, maybe in future there will be option to make it delayed but now it is exactly as majority of our customers wants.
Of course if this feature would be asked for by more people then we would think about it seriously.

and second question - this has potential so I will add it to requested features and we will see if it will be implemented or not.

Hi Jan,
Thanks for the reply.

“Instantly” would be great but in my case it is very much not instant, as I said it takes 2-3s at best, minutes at worst. Perhaps you do much of your own testing with a fast connection to a local server??

Duration is of course completely different from frequency - “too often” is what I reported a problem with. It would be reasonable to sync instantly after I’ve made a change, but that’s not whats happening, it occurs after every scroll. 2-3 seconds per scroll - I would have laughed at that on Windows 98, so obviously it’s ridiculous in the modern era.

I’m beginning to wonder how many customers you have using CalDAV. I’ve tried to persevere with it because I think it has potential, but currently it’s unusable, even worse than lightning, so I’m back with Thunderbird.

I would report more of the bugs I’ve found or even Beta test if I were convinced there would ultimately be a good product. I would buy licenses willingly if only it worked for my needs.



please try this version, there were made some changes to CalDav and it might help you with your problems.…


Hi Jan,
There’s no change on this one. With the “operations” window open it’s quite clear - there is a full sync for every scroll, change of view, etc. It takes 2-3s for me in good conditions, can take minutes in bad. Calendar is unusable in meantime. Data usage cost would be extortionate using mobile internet.

Please can you confirm you see the same? If so, do you agree this is a problem? If some users like it as it is, then the obvious answer is to have an option.



I do understand that this is problem for you, by no chance I am denying it. We simply focus now on more demanded features.
As I have written it is not thrown over board and it will be considered, but not in close future.

BUt I will put this into requested features because I see that this can help people using mobile internet.

with regards

Hi Jan,
Thanks for your reply. Just so you know - I have cable broadband myself and I still see 2-3s delays - I mentioned the mobile internet as it is relevant to others.

I doubt this feature will get requested much, as people make requests if they basically like your software but find it lacking in some way.

With this problem, a bunch of people will try it, and right away say “eM client sucks it’s so slow, immediate uninstall”. A bunch more will think “it’s rather slow, well that’s just how things are”.

I’m unusual, being a professional programmer, that I can see it’s slow, figure out why, and know that it very very easily could be much better. I recommend you fix it as it will stop you losing that first bunch of customers, and that second bunch will thank you for much improved speed.

I can explain how I would fix it if it were my program if that would help - probably only a few hours work.



well If you have some idea you can contact this person: and talk trough to him as this is off limits what I can do, promise or arrange.


@adam: i have your same problem, and a workaround!
@Jan:i think you misunderstood Adam’s explanation.

I’m experiencing the same issue, that is, em Client is syncing NOT ONLY after data modification and every X configured minutes, as it is supposed to do, but ‘whenever you change view, change week, scroll, or do more or less anything’.

That is, even if you don’t change any data, and even disabling scheduled syncs, em Client perform a resync for almost every click on calendar or task user interface!
And this can’t be a normal or expected behavior, it makes em Client unusable (especially on slow connections).
It seems a bug, perhaps caused by a specific combination of em Client / CalDAV server / configuration (my server is ownCloud, if you want i can provide more details).

And the workaround is: use a non filtering Search folder instead of the ‘main’ Calendar/Tasks.

  • Make emClient show the ‘Search’ text box (in Tasks it should be always displayed, in ‘Calendar’ select the ‘Agenda’ view)
  • Click the little down arrow on the right and select ‘Create search folder…’. Name it something like ‘All’.

You didn’t specify any filters, so this search folder will display all your data. And WITHOUT the annoying resyncs!

Hope this helps.

btw: this addresses also this thread:…


thank you for this explanation and making things clear.

best regards

Hi Jan,

any ideas by when this bug will be fixed?




one of my previous answers is still in place, we now focus on features which requires more attention.

Anyway I have this topic bookmarked so I will point it out again after we will release 6th version (now we are having quite alot work with it)

I hope you will understand this.

with regards

I am evaluating eM Client and the only problem that stops me is the very confusing, time consuming and annoying syncronizing behaviour whith CalDav source. Every time I change view or scroll in the calendar, it syncronizes and do it very slow.

Has this been an issue in earlier versions also? Has this been reported before?

Please consider to do a bug fix on this very unsatisfying problem.



this is actually behaviour like it is designed, we do not plan to change this.

with regards

Well if you have designed it to be unusable with poor connection then that’s up to you. The CalDAV specification and the rest of the world match my suggestion, and for good reason.

I’ve already uninstalled anyway. Although Thunderbird is in many ways frustrating, emClient, although initially promising, manages to be worse and expects me to pay.

It is designed to be always actual, to be honest calendar with outdated information is useless.
Anyway developers will check on this if it is possible to make CalDAV not synchronizing all the time to be optional.

with regards


Up to now I’m using Thunderbird and Lightning and it’s ok. Not very user friendly, but no major bugs.
When searching the web, I found eM Client and it looks nice. A complete groupware, which syncs with my cyrus imap and owncloud calendar and contacts. My Server is in the same network, speed is fine.
But I’ve detected the same problem as the topic reporter.

Are you serious? Customers want a behaviour of disappearing events during scrolling??? Unbelievable …
Even if eM Client wants to refresh at click event, why have the events to disappears for a short time? Why no refresh in background?

Unfortunately the workaround from Irisquota doesn’t work for me. Constantly refresh, no config possibility.

Please, if you want to earn money, fix such bugs, ok?
And don’t tell us, such behaviour “is not a bug, it’s a feature”. Software should fit user’s needs, not developer’s dreams…

Greetings, Uwe

Hello, my previous answer still pays. User wants to have updated calendar and there is no other way how to do it without technical difficulties.


i have the same issue:
after scrolling down, calendar is syncing. event disappearing…

What is with Laoptops? It should be possible to use the caldav calendar in “offline” modus…

take a look at evolution mail on linux…


I think the problem is not the sync is done quite often, that is ok. What is not ok is that all items disappear/reappear during sync and you can’t actually work with the calendar. Take a look at how this issue is handled on Thunderbird/Lightning or iOS devices. I can use the same calendar server over the same internet connection but do not get this annoying effect like on eM Client. You can sync often, but you should make the items just stay one the screen and update without visual disturbance, e.g. only deleted items disappear, only items that have been change move in the respective view.