vm1.vhd is corrupt

Hi!
 

While taking backup of a Hyper-v server we are getting messages

Verify:

vm1.vhd is corrupt.

and

Backup:

Backup Exec failed to connect to virtual machine 'vm1' and was unable to collect the necessary metadata to restore individual application items. You cannot perform GRT-enabled restores of application data from this backup. You must install the agent for windows and the virtual machine tools provided by your host software on the virtual machine.

and

Backup:

Failed to mount one or more virtual disk images. Restart the backup exec server to address this issue.

Thanks.