Error connecting to server

Problem

After synchronization, a popup appears at the top of the screen saying that an error has occurred. After clicking the button, the error details state the following:

A connection with the server could not be established

---> System.Exception: The text associated with this error code could not be found.

Cause

This error can have multiple causes. Here are some possible causes. It's possible this list is not exhausting.

• An add blocker that is installed in your browser is blocking traffic from/to OneCalendar. This can be caused by a recent update of the add blocker.
• A Windows update has caused traffic from/to OneCalendar to be blocked.
• The VPN connection is blocking traffic from/to OneCalendar. This can be caused by a recent update of the VPN client.