Google contacts and calendar not working anymore - emclient crashing after a while

I am working quite fine with the sync to google for some time now. Now I get the error “Execution of the authentification request returned unexspected result”. User and password are correct. I deinstalled and installed emclient again. No effect.
I am running Win8.1 with all updates. Also emclient is the newest version.
One more problem on top: after a while emclient is cancelling itself showing a window programm error.


Same problem for me syncing towards Google calendar.
Seems like it has been a change in google API or something on May26th

Any emclent developers looking at this?



Same with me, started only a few days ago and is very frustrating!!


Google calendar syncs just fine but with contacts I get: error 404()


I can confirm the Google calendar (and contacts) sync issue.

I get this error:
10:08:40   MailExceptions.OperationException: Synchronizing folder ‘’ failed due to the following error: Execution of authentication request returned unexpected result: 404 ()

Any known work-arounds?

Best regards

Hello, unfortunately we’ve came across this issue with a couple of installations, can you please try to re-setup the account in eM Client this should allow you to synchronize the account without any additional errors.
This unfortunately occured due to Google disabling the previous authentication method for use with eM Client Google accounts, but should occur no longer on a newly created account.


    I’m on version 5.0.19406.0

I’m having this problem.  After deleting and re-adding the account it didn’t pick up (or I believe try to sync) the Gmail Contacts and Calendar (i.e., nothing showing).

So I disabled and re-enabled the service.  It tried to sync but threw up the same authentication error messages.

What next?

John H.

Hello John, unfortunately it is no longer possible to use eM Client 5 with the Google Calendar/Contacts services, as I suggested unfortunately the company has shutdown support for authentication using a different method than OAuth 2, which is the new standard for authenticating with this service.

You can upgrade to eM Client 6 which already allows you to use the calendar using this authentication option.

Hope this helps,

Thanks Paul.  I figured you were going to say something like that.   :-((

I’ve done but it’s the same problem anyway and it’s absolutely disgusting and irritating. It’s not possible to use the client cos there’s always this error. ((

Hello Irina, have you re-setup the account in the latest release of eM Client? What version of eM Client are you currently using on your computer, can you please check the exact release number in Help > About? Can you please make a screenshot of the error and of your account settings from Tools > Accounts > Your account?

Thank you,


I am running 6.022344 version on window…  So as I understand your last comment was to delete the account setup for gmail and setup a new account.   I do use two factor auth so I will have to generate a new key correct…  since the existing key is not recoverable.

Unfortunately we do not currently have any other option to work-around this issue. Please make sure to let us know if you need any further assistance with the setup.


I have just starting getting the same problem. I upgraded to 6.0.22344.0, but still got the error. I tried disabling the service and re-enabling, but then all my calendar entries were deleted.

I killed emClient, and restarted, and now I seem to have my calendar back. But I still get the sync error, which is very annoying. If I can’t get this fixed, I will have to migrate to an alternative application. Help!



I deleted my account and created a new one for email and a new one for google calendar. This fixed the issue for me.

I’m using emClient version 6.0.22344.0.


Hello Oliver, can you try to re-setup the account, this is unfortunately a global Gmail issue, that we as well as other applications were unable to avoid prior to shutdown of the old API’s.

Thank you,

Hello Brian, thank you for following up with us, glad it works, please make sure to let us know if you come across any other issues or questions about the application, we’ll be happy to help.