Docker Error - Error initializing network controller: could not delete the default bridge network

Docker service is not starting because of following error.

Starting Docker Application Container Engine...
level=info msg="[graphdriver] using prior storage driver \"aufs\""
level=info msg="Graph migration to content-addressability took 0.00 seconds"
level=info msg="Firewalld running: false"
level=fatal msg="Error starting daemon: Error initializing network controller: could not delete the default bridge network: network bridge has active endpoints"
docker.service: Main process exited, code=exited, status=1/FAILURE
Failed to start Docker Application Container Engine.
docker.service: Unit entered failed state.
docker.service: Failed with result 'exit-code'.

Solution :
Remove /var/lib/docker/network folder.

I moved the folder to home dir and restarted docker as I thought if something is broken, I can replace it again to its original place but nothing was broken, I did not need the folder again and the error was gone. I could restart docker successfully.