In order to try to help we need a lot more information than just the error you are getting.

What version of Veeam are you using including build number?  What OS?  What task are you performing when this happens?

Did you check the logs for clues - C:\ProgramData\Veeam\Backup\Jobname

Hi ​@ketan,

I agree with Chris - since there is absolutely no information in your request, we can only try to suggest.

I saw this message multiple times when trying to directly access SAN (storage devices) from a proxy node, this issue could be caused by missing or outdated drives, mismatches in SAN zoning or simple an outage or reboot of the SAN target you might be trying to access.

We definitely need more details. In case this is an urgent issue please consider opening a Veeam support case.