Help troubleshooting error "an existing connection was forcibly closed by the remote host (Zoom)"

API and Webhooks
1

Hello!

We are working on implementing the Zoom API for an internal project, but we are encountering an error that we have been unable to troubleshoot from our end.

API Endpoint(s) and/or Zoom API Event(s)
Any endpoint.

Error & Description
Specifically, we get the following error when trying to connect to any API endpoint:

"Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host..
System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host..
—> System.Net.Sockets.SocketException (10054): An existing connection was forcibly closed by the remote host.

This does not happen in our local dev nor Azure test environments, where we’re able to connect to the API as expected. We’ve attempted to get more detailed logging out of C#/.NET (which our internal project uses) and from Wireshark with little success. We can see the RST packets in Wireshark, but that hasn’t gotten us closer to a solution.

I have reviewed relevant posts on the Zoom Developer forum, and I have tested forcing a compatible TLS version in C# as suggested in some threads. We have also confirmed that we are using compatible cyphers (as shown in the Zoom documentation, which the forum is not allowing me to link to at the moment).

How To Reproduce
Any calls to the Zoom API originating from the affected environment will produce the error. Due to the internal nature of the project, I cannot publicly share any endpoints or more detailed logs in this post.

Any help would be greatly appreciated!

Thank you,

Ryan

2

Hi @user145
Thanks for reaching out to us!
Are you still having this issue? I have not seen this error on our end

3

Elisa,

Thanks for the response!

Yes, we are still experiencing this issue. As mentioned in the OP, the same app/code is working when deployed to 2 other locations. Like the working locations, the affected location has a valid SSL cert and the correct TLS version/cyphers. And the 80 & 443 ports appear to be accessible as expected.

Please let me know if I can DM you additional details.

4

Hi @user145
Sure thing, let me send you a DM and you can send. me more details ther

5

For anyone who stumbles upon this thread in the future: although I can’t provide any additional information, this issue ended up being related to our firewall blocking some zoom.us traffic. If you’re experiencing a similar issue, be sure to check your firewall!

1 Like
6

Hi @user145
Thank you for reporting back and for sharing your findings with the broader community.

1 Like
7

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