How to change binding port of Docker private repository in Nexus by using configuration file?

  docker, nexus

After I changed the https port of my docker private repository to 9999 and restart nexus, I got the error: admin – Could not start connector: DockerConnectorConfiguration{repositoryName=bidv-docker-private, scheme=https, port=9999} Failed to bind to /

Caused by: Address already in use
at Method)

I knew that I choosed a port that already in use. But after I kill the process that running this port. The error still happened, and I could not find any configuration file to change it manually

Can you help me ? Which is configuration file for changing HTTPS port docker private registry ?

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Source: Docker Questions