Ngrok tunnel not found error

[ShadiyaIffath]

Bug report for Colab: http://colab.research.google.com/.

For questions about colab usage, please use stackoverflow.

• Describe the current behavior: I am trying to get Ngrok work with flask in Colab.

Tunnel 81a3868a65bb.ngrok.io not found

• Describe the expected behavior:

I have been using ngrok with flask in google Colab for almost 4 months now and it has been working perfectly until recently (January 2021). Including me several other users have raised a question in stackoverflow in the tunnel not being found error. When the tunnel is created in my local machine the tunnel is opened, hence this is not a problem with Ngrok.

• The web browser you are using (Chrome, Firefox, Safari, etc.): Chrome

• Link (not screenshot!) to a minimal, public, self-contained notebook that reproduces this issue (click the Share button, then Get Shareable Link): https://colab.research.google.com/drive/1O_zANJWS0IQsDCYIq1_XZkbueL0d4HXx?usp=sharing

Thank you for your assistance

[alexdlaird]

I've seen this now numerous times on Stack Overflow in the last week. Tutorials that used to work now don't, simple tunnels that work locally and/or on other machines (and previously to work in Colab) now say "Tunnel xyz not found" when the tunnel URL is visited, as described above.

If you start a tunnel using an auth token and visit https://dashboard.ngrok.io, you can see that your tunnel is started successfully, so ngrok and pyngrok appear to be doing their job. Feels like Colab has suddenly started blocking the connection to such tunnels.

[colaboratory-team]

This sounds like an ngrok service issue. Consider following up with the ngrok maintainers on the ngrok issue tracker at https://github.com/inconshreveable/ngrok/issues.

[alexdlaird]

The above issue tracker is for the legacy ngrok 1.x, which is no longer maintained or supported. https://www.ngrok.com is the right place to ask for support now, which I have done.

Thanks for the response.

[alexdlaird]

I will also note, if you add something like urllib.request.urlopen(external_url).read() to the shared Colab notebook, the tunnel is found and the request succeeds. So the tunnel can be found if the request is issued internally—defeats the purpose of ngrok then, of course, but perhaps useful in understanding where the connection is being blocked.

[alexdlaird]

ngrok support got back to me, they were accidentally blocking Colab as of the last week. They have now resolved the issue. Just wanted to leave this here in case others find this thread.

[ShadiyaIffath]

Thank you so much @alexdlaird for your help in fixing the problem and for the kind tip in figuring out where the connection gets blocked at, that's really helpful. @colaboratory-team thank you for the prompt response for my issue.

[romellfudi]

I've had this issue again, @ShadiyaIffath @alexdlaird Is it possible ngrok are anew blocking Colab ? update: Just put any port when you start running