Forum Discussion
Websocket connections to critical Microsoft 365 domains
We continue to get warnings on our tenant regarding Websocket connectivity errors.
Full message states:
We've detected WebSocket Secure (WSS) failures to the following unified domains.
I can't publish the wildcarded URLs here, but you'll know the ones I mean from your M365 admin networking connectivity insights page.
I don't understand this as we effectively have those domains whitelisted/bypassing https inspection etc and everything seems to be working as normal. Nothing has been changed as far I'm aware.
Anyone else seen this warning in their tenancy? Anything else we can check or try to sort the issue. Or is it just something to note??
We have a support ticket in - but on doing the initial check nothing is showing up.
Our networking team have confirmed with me that the connection sends data to Microsoft uninspected. For that reason, it shouldn’t cause the websocket errors that are being reported.
3 Replies
- Roshan_Sabapaty
Microsoft
Please check the status of websocket connection using Microsoft 365 Copilot network connectivity test if you suspect any issue with it, if the web tool returns success then there is no action needed from your side, based on your writeup I am guessing there are no websocket issues. Regarding the network insight notification for websocket connectivity errors, we are updating the mechanism for websocket connection tests reporting and if you have already raised this issue with support, I am almost certain that this should go away for your tenant in the coming weeks.
- Ares Chen
We have a support ticket in
can you share the ticket number to me? I will follow up with this.
Worth to take a loo at this:
- Check Firewall & Proxy Rules
- Ensure WebSocket traffic is explicitly allowed for Microsoft 365 domains (*.cloud.microsoft, *.static.microsoft, etc.).
- Some proxies may still block WebSocket connections even if HTTPS inspection is bypassed.
- Verify Microsoft 365 Network Insights
- Go to Microsoft 365 Admin Center → Network Connectivity Insights.
- Look for any service health notifications related to WebSocket failures.
- Test WebSocket Connectivity
- Use tools like wss://echo.websocket.org to verify WebSocket connections.
- If external WebSocket connections work but Microsoft 365 fails, the issue is likely tenant-specific.
- Check TLS Decryption Settings
- Some security appliances perform TLS decryption, which can interfere with WebSocket traffic.
- Ensure Microsoft 365 domains are excluded from TLS decryption.
