I had this exact same problem. I noticed that tgt had been installed and was running (that's what must have been using 0.0.0.0:3260). So I killed the tgt process and then was able to create the portal with the default 3260 port in targetcli.
I had this exact same problem. I noticed that tgt had been installed and was running (that's what must have been using 0.0.0.0:3260). So I killed the tgt process and then was able to create the portal with the default 3260 port in targetcli.