VSS Trouble Shooting

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With the VSS Troubleshooting Guide you can solve common VSS problems.

VSS in SEP sesam

SEP sesam installed never own VSS components. SEP sesam use only the VSS components, provided by Microsoft.
VSS allows rapid "point-in-time" snapshot of a hard drive for backup jobs.

When you have a VSS error, follow the steps below. Test after each step if the problem is resolved:

Windows reboot

Step 1:
Reboot your Windows. A Windows reboot often eliminates various VSS writer problems.

Disk space

Step 2:
If insufficient disk space is available, VSS snapshots may fails.
Check if sufficient disk space is available.

Multiple Backup Jobs with VSS

Step 3:
It is not possible to run multiple VSS snapshots at the same time, Windows can only start a VSS snapshot for each partition.
If multiple VSS jobs are started, the operating system reports the following VSS error message: VSS_E_SNAPSHOT_SET_IN_PROGRESS


To avoid general such VSS errors, run the backup jobs from a client sequentially, such as:

  • 22:00: Start System Recovery Backup
  • 23:00: Start Custom Path Backup


If the temporal separation is not possible, try the following solution.
These must be set in the sm.ini following settings on the client:

[SBC_OPTIONS]
VSS_WAIT_FOR_ASYNC_OP=180
VSS_DELAY=90
VSS_MAX_RETRY=6

With these settings, the VSS VSS sesam Client tries to execute operations sequentially and waits for an active VSS operations.
The "matching" settings may vary depending on system and backup jobs.

Third-party Backup software

Step 4:
Please check if another backup software from another vendor is running on the system, such as:

  • Windows Backup, NTbackup
  • Acronis, Backup Exec, ect.

Disable this backup software if necessary.

Remove old VSS snapshots

Step 5:
Start the CMD command prompt as administrator and type the following command:
vssadmin delete shadows /all


The command cleans up all VSS snapshots of all volumes.

VSS writer status check

Step 6:
Start the CMD command prompt as administrator and type the following command:
vssadmin list writers


If a VSS writer error appears, restart the following services:

  • Volume Shadow Copy Service
  • VSS application writer (Exchange, MS-SQL, Hyper-V)
  • COM+ System Application Service
  • Distributed Transaction Coordinator Service

Run the command vssadmin list writers again, and check if the issue is resolved.

Windows event log check

Step 7:
Check the event logs of the Windows Event Viewer. Search for "VolSnap" errors, the fit for "vss" and at the time of the SEP sesam backup job.
Often it helps, to search the Internet for the event ID of the fault to get an indication of the error cause.

Re-register VSS and COM+ components

Step 8:
The following scripts re-register all VSS and COM+ components.


Copy the follow commands in a new *.bat file. Start the batch script in the command line as administrator:

For 64bit and 32bit systems:

cd /d %windir%\system32
Net stop vss
Net stop swprv
regsvr32 ole32.dll
regsvr32 vss_ps.dll
Vssvc /Register
regsvr32 /i swprv.dll
regsvr32 /i eventcls.dll
regsvr32 es.dll
regsvr32 stdprov.dll
regsvr32 vssui.dll
regsvr32 msxml.dll
regsvr32 msxml3.dll
regsvr32 msxml4.dll
regsvr32 Vssapi.dll
regsvr32 Vssui.dll
net start vss
net start swprv

Step 9:
Copy the follow commands in a new *.bat file. Start the batch script in the command line as administrator:

For 64bit systems:

Net stop vss
Net stop swprv
regsvr32.exe /i %windir%\system32\eventcls.dll
regsvr32.exe /i %windir%\system32\swprv.dll
regsvr32.exe %windir%\system32\vssui.dll
regsvr32.exe %windir%\SysWOW64\vss_ps.dll
regsvr32.exe %windir%\SysWOW64\msxml.dll
regsvr32.exe %windir%\SysWOW64\msxml2.dll
regsvr32.exe %windir%\SysWOW64\msxml3.dll
regsvr32.exe %windir%\SysWOW64\msxml4.dll
regsvr32.exe %windir%\SysWOW64\ole32.dll
regsvr32.exe %windir%\SysWOW64\oleaut32.dll
regsvr32.exe %windir%\SysWOW64\es.dll
regsvr32.exe %windir%\SysWOW64\comsvcs.dll
vssvc /register
net start swprv
net start vss
net stop winmgmt
regsvr32 wmiutils.dll  
net start winmgmt 

VM utility Update

Step 10:
If the system is a virtual machine:
Uninstall the installed utility version and start the VM. Then reinstall the latest VM utility version:

  • VMware vSphere: VMware Tools
  • Microsoft Hyper-V: Hyper-V Integration Services
  • Citrix XenServer: XenServer Tools

Windows Update

Step 11:
Install the latest Windows updates, service packs and hot fixes from Microsoft.
Test it again after the update.