Why does my login to Microsoft 365 expire and I have to sign in again?

Issue
When opening or previewing documents from FYI, I am prompted to sign into my Microsoft 365 account before it can be opened. But after signing in, it stays logged in for a while but it then expires and I have to sign in again.

Refer to Previewing an Email and Previewing a Document.

Cause
The two most likely causes requiring you to sign in again are:

• The OneDrive session has expired. Sessions can expire when users are inactive, close the browser or tab they have been working in or their authentication token expires. This is a Microsoft 365 security setting and is not an FYI setting. Refer also to the Microsoft article Session timeouts for Microsoft 365
• The user's browser clearing credentials are removing the session when the browser or tab are closed.

Solution
You will need to sign in again each time this happens.

You may like to discuss this with your IT provider as they may be able to assist you in resolving the issue.