This is what I got while trying to format a partition in my pendrive:
Error deleting partition
parted --script "/dev/sdb" "rm 1"'exited with non-zero exit status 1: Warning:
/dev/sdbcontains GPT signatures, indicating that it has a GPT table. However, it does not have a valid fake msdos partition table, as it should. Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables. Or perhaps you deleted the GPT table, and are now using an msdos partition table. Is this a GPT partition table?
Error: Both the primary and backup GPT tables are corrupt. Try making a fresh table, and using Parted's rescue feature to recover partitions.