VM backups failing with 156 error in 7.5 Version. Please help me any one how to resolve this issue.
You give us nothing to work with...
Status 156 is a generic error saying that the snapshot creation failed.
Have you checked and confirmed all requirements? Such as vmtools installed on all VMs?
Can you use vSphere Client and manually create snapshots?
See this TN for some reasons for status 156: http://www.symantec.com/docs/HOWTO44492
Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and Windows
Handy NBU Links