Script error: VSS: Can't read volume data

I am using the free edition of Paragon Backup and Recovery 2013, version 10.1.19.16240 (22.11.12 ) Free

I am using Windows 7, 64 bit

I have had no issues with this software so far and have backed up two of my hard drives. I have tried to back up my third hard drive and get this error:

Script error: VSS: Can't read volume data

It is an external hard drive. It has been used to put backups ON but I cannot back this drive up.

Does the free version not back up external hard drives?

Any other suggestions?

Thank you!!!!

 

Error 0x12016 "VSS: Can't read volume data" usually means that source partition has bad blocks or file system errors.

Please run chkdsk utility for your external drive first.
You can run check from Tools tab in Properties window of your external drive , please enable all custom checkboxed before running file system check.
Or using command prompt:
chkdsk /r X:
where X should be replaced with the required drive letter.

You might have to run CHKDSK several times to get all errors fixed.
If it doesn't help, please try to backup from Recovery media.

BTW: what is file system type (NTFS or FAT32) of your external drive?