Windows was unable to complete the format

This error message may appear when you try to format a drive for use.

Possible reasons and workarounds

Sometimes, you cannot format the drive to the FAT filesystem if it has been formatted to a filesystem which is not recognized by Windows. Such a drive should be reformatted to NTFS first, and then to the FAT filesystem.
It is possible to have complex combinations of incompatibilities in the drivers or BIOS which result in such an error. It makes sense to try to format the drive on another computer. In most cases, the incompatibility problem only concerns the format procedure; once the drive is formatted, it would work fine.
There is a bad sector in the area that is required for a filesystem, e.g. for a boot sector or the FAT table sector. Since such a drive is obviously not possible to use, Windows refuses to format it.