Oracle Message ORA-16087 - graceful switchover requires standby or current control file

ERRORgraceful switchover requires standby or current control file
CAUSEAn attempt was made to perform a graceful switchover operation using a backup or clone control file.
ACTIONConvert the backup control file into a current control file prior to attempting a graceful switchover operation. A clone control file cannot be used for a graceful switchover operation.