NetWorker: Azure VM Snapshot Backups Fail "Failure when receiving data from the peer(curl error code: 56), Error while copying snapshot to DD"

Summary: NetWorker Azure Virtual Machine (VM) Snapshot backups intermittently fail with the error "Failure when receiving data from the peer(curl error code: 56), Error while copying snapshot to DD." This error appears randomly, during some backups the VM succeeds, on other backups, this failure is observed. ...

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Symptoms

Azure Virtual Machine (VM) backups performed through NetWorker intermittently fail with the following error observed in the backup action log:

207705:nsrazure_save: Curl: Error setting options/performing in curl, error details: Failure when receiving data from the peer(curl error code: 56), Error while copying snapshot to DD
207650:nsrazure_save: azurvmbackup: snapshot VM-NAME_DISK-NAME_SNAPSHOT-TIMESTAMP copy to DD failed
207820:nsrazure_save:Cannot backup to DD.  Backup of saveset: RESOURCE-GROUP-NAME:VM-NAME:VM-NAME_DISK-NAME failed.

Cause

The curl 56 error is a general network-connection error code. Common causes are:

  • TLS handshake issues
  • Connection reset by peer (server closed the connection unexpectedly).
  • Firewall or security interference.
  • Timeouts or packet loss during data transfer

The nsrazure_save command is encountering a curl communication issue and aborting the job without retrying the connection. Impacted versions:

  • 19.11.0.x
  • 19.12.0.x
  • 19.13.0.x

Resolution

Retry logic is to be added to NetWorker 19.14.0.0. Upgrade the NetWorker clients to this release (or later) for a code fix.

NOTE: The code change does not resolve the curl connection failure as this is occurring outside of NetWorker. The code change provides "retry" function when this connection issue is encountered. The same "curl error code: 56" messaging may be found in the logs; however you see "Retrying from offset" and the connection resumes. Each save set only attempts to retry 50 times. By default, the NetWorker policy has a "one retry" setting. Meaning, if the save set fails, the policy attempts the back-up again. If the connection fails more than 50 times again, the save set fails to backup. Excessive network connection failures must be investigated at the Azure level.

The following example is from a backup session using NetWorker 19.14.0.0. The backup log shows that it retries the session from last offset when "curl error code: 56" is encountered.

207705:nsrazure_save: Curl: Error setting options/performing in curl, error details: Failure when receiving data from the peer(curl error code: 56), Error while copying snapshot to DD
210931:nsrazure_save: Data transfer failed.  Retrying from offset 29284630528...
207705:nsrazure_save: Curl: Error setting options/performing in curl, error details: Failure when receiving data from the peer(curl error code: 56), Error while copying snapshot to DD
210931:nsrazure_save: Data transfer failed.  Retrying from offset 32025608192...

Products

NetWorker Family, NetWorker
Article Properties
Article Number: 000361593
Article Type: Solution
Last Modified: 27 مارس 2026
Version:  10
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