An attempt was made to remove an IP address from a port that was used to establish backend controller sessions. Removing an IP address through which sessions are established puts mdisks into a degraded state and is not permitted.
Use the management GUI or the rmiscsistorageport command to remove sessions through the source port before you remove an IP address that is used for backend controller connectivity. Alternatively, if the intent is only to remove the IP and then configure a new IP, you can achieve the same goal by using the cfgportip command with a -force flag.