The error from main.log indicates that the port 8443 is in use by another application/process. This also matches with the UNIX error 17 - which means file already open. (Sockets in *nix systems are files)
There is a bug in Postman client which causes it to crash when it tries to bind to ports for the interceptor proxy. Ideally, it should let you know that the ports are already in use.
Workarounds
- Update the port value before starting the capture
- Kill/quit the process/app using the port and try again.
- Something like the following should help to find the process using the port
lsof -nP -i4TCP:8443 | grep LISTEN
- Something like the following should help to find the process using the port
Notes
Postman proxy seems to be binding to two addresses, one with the port specified in the setting and one always with 8443