So, I installed Experience Builder SDK successfully on our production portal, but then tried to move it to our test portal.
I've been able to change the "https://localhost:3001/" to use the Client ID from the Experience Builder credentials on the test portal. (Note: I have already deleted the Experience Builder Credentials from the production portal.)
However, when I try npm start from the windows command prompt, I get the EADDRINUSE error, errno -4091 on port 3000.
I tried:
netstat -ano -p tcp |find "3000"
taskkill /F /PID <PID>
where <PID> is the far-right number from the netstat command, as described in this post: https://community.esri.com/t5/arcgis-experience-builder-questions/arcgis-experience-builder-uninstal...
However, I still get the same error. Any advice on how to uninstall and reinstall Experience Builder SDK?