Currently, Jupyter notebooks will not open in ArcGIS Pro if you are using a http_proxy environment variable at the system or user level. Many users are required to use a proxy setting due to department policies and therefore can no longer use notebooks.
I suspect this is a network level config issue - with the proxy or with another level of security that impacts the interaction between the notebook server and client components. Can you test and run another web service on the local machine? Something portable like XAMPP is handy for this.
Edit:
Both ArcGISPro.exe and python.exe open a number of listening ports (on 127.0.0.1 rather than 0.0.0.0 fwiw) when you open /add a notebook. If the proxy is a consume all rather than just for specific web service ports / ips you'll have issues. I don't think this is an Idea - rather work with IT and Esri to figure out the correct configuration.
I've had similar issues when doing things over some VPNs.
We are closing this post as it is a technical issue (as opposed to an idea). However, just because it isn’t the right fit as an Idea does not mean that we aren’t here to help.
"Pro Notebooks leverage a webserver run aslocalhoston port 8778. If you've not set an exclusion on your proxy settings to preventlocalhost:8778(or 127.0.0.1:8778) from going through the proxy, it will fail authentication and will be given a http 407 error in response (which it cannot handle) and fail.
You'll need to work with your IT group to add this exclusion, depending on the proxy you use and how it is implemented."
If you need further assistance, please reach out to Technical Support.
