Teams Tab App Cannot Reach server




I’ve been trying to host my Teams tab app using Tomcat on the same PC where Teams is running (i.e. localhost) with TLS enabled but I can’t seem to get it to work. Teams cannot display a simple page with HTML.


I know Tomcat is working  because I can display a page using a web browser with “https”.  I also know Teams can display a page with “https” because I can use Tomcat without TLS enabled and then map the “https” requests to “http” using ngrok.


My Teams app is hosted on port 443. Is the right port for a Teams app? I also configured the the manifest file with:

"staticTabs":[{ . . . "contentUrl": "https://localhost/gctest/index2.html", . . .}],
"validDomains": ["localhost"]


I also tried replacing "localhost" and something else that was mapped to in my Windows hosts file but that did not work either. Is there something I need to configure in the manifest.json file and/or Azure AD to get this to work?


I used the Wireshark application to capture the packets. I'm seeing the "Encrypted Alert" message:



Does this indicate a problem with my Teams app configuration?







2 Replies
best response confirmed by George71 (Contributor)

@George, Teams doesn't allow local hosting. You'll need to either publish your tab to a public URL, or use a proxy that will expose your local port to an internet-facing URL. Please use ngrok and try the same .

The content url would be like this contentUrl": "ngrokurl/index2.html".

Please refer the doc.

Thanks! That would explain why I could not get it to work. :)