iATKOS Inside: Each time I format a partition ( trying to dualboot windows 7 and macOS Sierra ) to macOS extended journaled it keeps giving this error - unmounting disk couldn’t modify partition map operation failed

Each time I format a partition ( trying to dualboot windows 7 and macOS Sierra ) to macOS extended journaled it keeps giving this error - unmounting disk couldn’t modify partition map operation failed

Unmounting disk Couldn’t modify partition map Operation failed