Eliminating VSS Error 8194 from Event Log
When you start the Backup program you may experience multiple instances of VSS Error 8194 in the Application event log. This tech note explains how to make the adjustments required to eliminate these messages from occurring in the Application event log.
The 8194 events are typically generated by the following services: System Writer (Cryptographic) service, NPS VSS Writer service, TS Gateway Writer service and (Windows) SP Search VSS Writer service. There may be others. The error is similar to the following taken from an SBS 2008 R2 system:
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Log Name: Application
Source: VSS
Date: 7/20/2011 11:16:01 PM
Event ID: 8194
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: MYSERVER.mydomain.local
Description:
Volume Shadow Copy Service error: Unexpected error querying for the IVssWriterCallback interface. hr = 0x80070005. This is often caused by incorrect security settings in either the writer or requestor process.
Operation:
Gathering Writer Data
Context:
Writer Class Id: {57af97e4-4a76-4ace-a756-d11e8f0294c7}
Writer Name: SPSearch VSS Writer
Writer Instance ID: {5c70a0f1-d237-4ae5-b9c3-a2bfce0f6517}
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Error code 8194 is an "Accessed Denied" error caused by the inability of one or more VSS system writers to communicate with the Remote Backup VSS requestor process via the "COM" calls exposed in the IVssWriterCallback interface (Microsoft programming interface to the Volume Shadow Service).
Solution:
To set the correct permissions and prevent the error from occurring, follow the instructions below:
- Press and hold the Windows key and press R to pull up the Run dialog. Alternatively, ifRun... is available from the Start Menu you can access it from there.
- Type dcomcnfg into the box and click OK. The Component Services window will appear.
- In the left portion of the window, expand the Component Services section and then expand the Computers section.
- Right-click on My Computer (listed in the Computers section) and select Propertiesfrom the pop-up menu.
- Click the COM Security tab. The My Computer Properties dialog will appear.
- Click the Edit Default... button in the Access Permissions section. The Access Permission dialog will appear.
- Under the Group or user names box, click the Add... button.
- Type Network Service into the box and click OK.
- Click OK on both the Access Permission and My Computer Properties dialogs to close them.
- Restart Windows.