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Windows 2008 server Backup with HyperV role fails

Event id 521 or others on W2k8 event log.
The backup operation that started at ‘‎xxxxxxxxxxxxxxxxxxxxxxxxx’ has failed because the Volume Shadow Copy Service operation to create a shadow copy of the volumes being backed up failed with following error code ‘2155348129’. Please review the event details for a solution, and then rerun the backup operation once the issue is resolved.
Step 1.
Fire up your cmd on the w2k8 server and check the vss writers
Vssadmin list writers
All should look like
Writer name: ‘xxxxxxxxxxxxxxxxxxxxxxxxxxxx’
   Writer Id: {xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx}
   Writer Instance Id: {xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx}
   State: [1] Stable
   Last error: No error
If all you writers have a state 1 Stable and last error is no error, then the problem is deeper and it comes from your virtual machines. If not first check the reason of vss failing and consult your event viewer for more details before going on.
There are 2 possible reasons for this behavior:
  1. Either there is no space left on –at least one of your VMs. Please note that free space for correct vss working should be at least 1GB for vhds of 100GB of space.
  2. Or at least one vss writer fails on one of your vms. Go back to step 1 and execute vssadmin list writers on every VM you have. At least one fails. On the one that fails (personally seen it on w2k3 Exchange VM were the Exchange Writer was on error) make a batch file containing the following (I have put some pauses in order to see who the procedure works out). Save the batch as whatever you like .bat and WATCH IT!!! Before Re-registering the vss and required dlls you have to switch your path to windows\system32!!! If you don’t, then the vss will not run actually and when you run vssadmin list writers nothing will come up. So pay attention!!!

Step1 :
Follow info on
Download and install update.

Open Cmd and run vssadmin list writers
No error should appear.
Check if backup works (It is likely it won’t, instead of running the whole W2k8 Hypervisor backup, try backing up the current VM by it’s own NTbackup, try system state or any folder)
If it does not work proceed to step3:

Locate and export the following key:
Export the key/folder somewhere in order to get it back if smt goes wrong
Now delete that key/folder (No worries Windows will recreate it)

Restart each of the following services in that exact order:
– COM+ Event System
– COM+ System Application
– Microsoft Software Shadow Copy Provider
– Volume Shadow Copy
If one of the services is on stop mode, change the startup type to automatic and start the service

Open Cmd and run vssadmin list writers
If errors still show up…go the last …step6

Watch it you have to switch your path to windows\system32 – otherwise you will see no writes in vssadmin.
Make a batch copy-pasting the following:

Net stop vss
net stop swprv
cd windows
cd system32
regsvr32 ole32.dll
regsvr32 oleaut32.dll
regsvr32 vss_ps.dll
vssvc /Register
regsvr32 /i swprv.dll
regsvr32 /i eventcls.dll
regsvr32 vss_ps.dll
vssvc /register
regsvr32 /i swprv.dll
regsvr32 es.dll
regsvr32 stdprov.dll
regsvr32 vssui.dll
regsvr32 msxml.dll
regsvr32 msxml3.dll
regsvr32 msxml4.dll
Net Start vss
Net Start swprv
vssadmin list writers
The batch will list vss writers at the end. Check if all are in stable.RESTART!!!!

Go back to your HyperV and try to back up.

You can check whether the backup runs at any time by running the VMs NTbackup- you don’t need to run the Hypervisor’s backup.
Hope it saves you some time.
Best regards,

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