Oracle Message ORA-12479 - file label string must equal DBHIGH string

ERRORfile label string must equal DBHIGH string
CAUSEA database file had an OS label that did not match DBHIGH. Either DBHIGH was altered or the OS file was relabeled.
ACTIONRelabel the file so that its label matches DBHIGH, or alter DBHIGH so that it matches the label on the file.