eM Client Calendar - problem syncing to Google Calendar

Everytime I add a new event in the eM Client Calendar, I get this error message:

[Google Calendar]Uploading event ‘Electric/plumbing La Montagne’ on 28-Jul-22 12:00:00 AM to calendar ‘johanrothmann@gmail.com/Calendar’ failed due to the following error: Request had invalid authentication credentials. Expected OAuth 2 access token, login cookie or other valid authentication credential. See Интеграция входа через Google в ваше веб-приложение  |  Google Sign-In for Websites  |  Google Developers.

The event is recorded in the eM Client Calendar, and appears in my Google Calendar after clicking on “Ignore All” and refreshing.

Why ?

Could be you may have an outdated version of eM Client that doesn’t support the later OAuth. What version of eM Client do you have and do you have Windows or Mac.

Also have you tried removing and re adding your Google account in eM Client via the automatic wizard ?

Thanks for your reply.
I am using eM Client version 8.2.1721 (3b3cd99) on a Windows 10 PC.

I have not tried to remove/add my Google account yet, but don’t have any problems with emails or contacts that sync to and from my Google account.

I am using eM Client version 8.2.1721 (3b3cd99) on a Windows 10 PC.

Ok. So your eM Client version is all up to date and np there.

I have not tried to remove/add my Google account yet, but don’t have any problems with emails or contacts that sync to and from my Google account.

Even though your Mail and Contacts are working ok due to the Google Calendar OAuth 2 issue i would still suggest to delete and re-add your entire Google account as new in eM Client.

Suggest to first backup eM Client via “Menu / Backup” and you can see when the backup is completed via clicking “Menu / Operations”.

Once backed up go to “Menu / Accounts” and click on your Google account on the left and click “Remove” along the top. Then finally click “Add account” and follow the “Automatic wizard” at the top and setup your Google account as new again in eM Client.

Recreating the oAuth token should resolve it without having to re-add the account.

Close eM Client an open your web browser.
Go to your Google Security settings page: https://myaccount.google.com/security
Go to Manage Third-party Access and remove eM Client.

Start eM Client and complete the web browser part of the authentication.