Avamar: Scheduled Hyper-V backups fail due to invalid DDR token

Summary: This article outlines a workaround for a known issue where scheduled Hyper-V backups fail in Avamar due to an invalid Data Domain (DDR) token. Manual backups are unaffected.

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
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Symptoms

Scheduled Hyper-V backup jobs may fail with errors similar to the following:

  • avhypervvss Error <19328>: Unable to forward CTL sub-workorder to remote client [HYPERV-HOST03].
  • avhypervvss Error <19366>: Unable to send sub-workorders to all remote clients.
  • avhypervvss Error <41659>: Backup did not complete successfully.
  • avhypervvss Error <43488>: PAX API 'beginfile:extents' reported error 32.
  • avhypervvss Error <43490>: Failed in begin file C:\ClusterStorage\Volume23\WEBT01\WEBT01-OS.vhdx for incremental backup.
  • avhypervvss Error <43486>: Failed to stream file '00000009\C:\ClusterStorage\Volume23\WEBT01\WEBT01-OS.vhdx...'.
  • avhypervvss Error <43488>: PAX API 'endfile:extents' reported error 32.
  • avhypervvss Error <43473>: Processing workorder in stream mode failed.
  • avhypervvss Error <43475>: Plugin exited with code 536870920: cannot establish connection with server (possible network or DNS failure).

Additional errors may appear in avtar and avagent.log:

  • avtar Error <41439>: Using invalid token.
  • avtar Error <10542>: DDR server open failed — Invalid API argument.
  • avtar Error <10509>: Problem logging into DDR server.
  • avagent.log:
    ctl_mcs_send ERROR <0001>: Failed to enqueue the MCS response for federated use case.

Manual backups complete successfully.


        
Cause

        
The issue is typically caused by delays in the Management Console Service (MCS) on the Avamar Utility Node when handling DDR token requests.

   These delays result in token timeouts, especially during peak backup activity across Avamar and Data Domain grids.

        
Resolution

        
Reschedule the Hyper-V backup jobs to run during off-peak hours when Avamar and Data Domain systems are less busy.

  
Example:

   If most backup jobs start at 8 PM, schedule Hyper-V backups to begin at 11 PM or later to avoid token timeout issues.

  
 


                    
Additional Information

        
Related KB:  Avamar: Hyper-V incremental backups failing with "invalid token" errors




        

        
        
Affected Products

        Avamar, Avamar Plug-in for Hyper-V VSS







                        

                            

    

        

            

                
                    
 Article Properties

                
            

            

                

                        
Article Number: 000200201

                

                
                

                        
Article Type: Solution

                

                

                        
Last Modified: 31 Oct 2025


                

                    

                            
Version:  2

                    


            


        

    

    

        

            

                
                    
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