Recent Windows 10 update blocks Microsoft Teams, Outlook logins

A recent Windows 10 1909 cumulative update prevents Microsoft 365 desktop users from logging into Microsoft Teams, Microsoft Outlook, and Microsoft OneDrive for Business.

When attempting to login, users are shown a message stating, "We ran into a problem. Reconnecting…" and asking the user to restart the program.

This same screen will also display an error code 80080300 at the bottom left of the screen, as shown below.

Microsoft Teams 80080300 error

This issue is caused by the Windows 10 1909 KB5003169 cumulative update released last week as part of the May 2021 Patch Tuesday updates.

To fix this issue, Microsoft states that you need to restart Windows 10 again after the update finishes installing.

"We've received reports that some users on Windows Update KB 5003169 are unable to connect to various Microsoft 365 desktop clients including Microsoft Teams, Outlook, and OneDrive for Business," Microsoft explains in a recent Microsoft 365 advisory.

"Our investigation has determined that a code issue exposed by a recently deployed Windows update, detailed in KB 5003169, is causing the problem."

Microsoft states that their telemetry indicates that only a small percentage of users are affected by this bug until they restart Windows 10.

If reboot Windows 10 does not resolve the issue, Microsoft recommends that you use the web versions of the Microsoft Teams, OneDrive for Business, and Outlook applications while they investigate the problem.