Applies To

Call2Teams - Customer


When clicking the Sync Now button, the authentication window does not pop up and the following error is shown:

"Unable to start the sync: Auth window closed"


This error occurs when the sync process initiates. 

An authentication pop-up window is needed to enter Microsoft 365 credentials (username & password).

The error explains that the popup window was closed prematurely before the authentication had taken place, either through manual action (closing the window purposefully) or due to a browser security setting preventing pop-up windows.


Check browser security settings and try the process again using an in-private browser session with one of these browser types:

  • Microsoft Edge
  • Firefox
  • Google Chrome

Please note Internet Explorer is not supported by the service portal.


  • Ensure any pop-up blockers are disabled.
  • Verify browser and workstation security settings allow pop-up windows.
  • Try the process on a different computer, preferably using a different network access such as a mobile hotspot.