Super quick post here. Sometimes when debugging your .NET Core application on Mac, you’ll find the port won’t free up, and thus you can’t redeploy without getting the following fatal error:
Unable to start Kestrel. System.IO.IOException: Failed to bind to address http://localhost:5000 on the IPv4 loopback interface: port already in use.
To fix this, you’ll need to fire up Terminal and enter the following:
▶ sudo lsof -i :5000
In my case, this outputted the following:
I know the error is referencing the IPv4 Type which allows me to quickly find the PID number, which I’ll use to kill the connection. I do this with the following command
▶ kill -9 18057
With that done, I can now get back to debugging my .Core web API on macOS.