I ran into this error when I tried to set my external hard drive to automatically mount to the same mount point on every reboot. First, I went into the disk utility in Ubuntu and got the file system type which was HPFS/NTFS. I got my UUID and entered this line into my fstab file:
UUID=b3a0378a-c352-47fe-ac88-cf2a9d815e13 /media/Backup HPFS/NTFS defaults 0 0
Then, I ran mount -a to remount everything in my fstab file but ran into this error:
mount: unknown filesystem type 'HPFS/NTFS'
I couldn't find a solution anywhere on the Internet but then remembered I set this drive to the ext4 file system when I formatted it. I changed my fstab file to reflect that:
UUID=b3a0378a-c352-47fe-ac88-cf2a9d815e13 /media/Backup ext4 defaults 0 0
After re-running mount -a everything worked.