Troubleshooting: Ubuntu Microsoft Teams Client Crashes When Signing In Through a SecureAuth Realm – SecureAuth Support

Version Affected: All

Overview

When the Microsoft Teams client on Ubuntu Linux is used to sign in through a SecureAuth realm integrated with an O365 application, the client repeatedly crashes and relaunches right after the user enters their email address, showing "Taking you to your organization's sign-on page" before crashing. The Teams client works normally on Windows, macOS, browsers, and mobile devices for the same realm, and the realm and Internet Information Services (IIS) logs on the SecureAuth Identity Provider (IdP) show no traffic arriving from the Ubuntu client at all during the failed sign-in attempt.

Cause

The Ubuntu Teams client is an Electron-based application, and its User-Agent string identifies it as such (for example, containing MicrosoftTeams-Preview and Electron tokens). A proxy or web application firewall (WAF) sitting in front of the IdP can misidentify this User-Agent as a bot and block the request before it ever reaches the IdP -- which is why no trace of the attempt appears in the IdP's own logs.

Resolution:

Check the proxy or WAF for a rule that is flagging and blocking this User-Agent string. For example, an F5 BIG-IP Bot Defense profile can classify an Electron-based client as an untrusted "headless browser" bot and issue a TCP Reset, denying the request outright:

An F5 BIG-IP Bot Defense incident log entry showing a request denied with a TCP Reset mitigation action, with the detected bot signature "Electron (Nightmare)" and the User-Agent string's Electron component highlighted.

Allow this User-Agent (or the specific bot signature the proxy/WAF assigns to it) so the request can reach the SecureAuth realm.

SecureAuth Knowledge Base Articles provide information based on specific use cases and may not apply to all appliances or configurations. Be advised that these instructions could cause harm to the environment if not followed correctly or if they do not apply to the current use case.

Customers are responsible for their own due diligence prior to utilizing this information and agree that SecureAuth is not liable for any issues caused by misconfiguration directly or indirectly related to SecureAuth products.