Repeated "Address already in use" when starting kernel

[jfschaefer]

Twice I had the problem that the kernel repeatedly failed to start.
It appears the desired port (20003) is already in use and it keeps trying to use that port.

Restarting jupyter did not help - only rebooting the laptop fixed it.

Here are the full logs.

Small excerpt:

Traceback (most recent call last):
  File "/usr/lib/python3.7/site-packages/py4j/java_gateway.py", line 2175, in start
    self.server_socket.bind((self.address, self.port))
OSError: [Errno 98] Address already in use