MARS throwing error 0x18758, VSS Service Encountered an Error

Question

SAN Policy is Online All

Not sure what else to try here folks.... Thanks. Has never worked on this Server, Windows Server 2022.

Answer 1

@Colin Schmitt I hope you are doing well

The MARS agent relies on VSS to create consistent snapshots for system state or file backups. The error 0x18758 is not well-documented in public sources, but it’s likely a generic VSS-related failure, similar to codes like 0x80042302 or 0x8078010E, which point to issues with VSS writers, services, or permissions. Common causes include:

• VSS Writer Failures: One or more VSS writers (e.g., System Writer, SQL Writer) are in a failed or timed-out state.
• Service Issues: The VSS service or related services (e.g., SPP, COM+ Event System) are misconfigured or stopped.
• Permissions: The MARS agent or VSS lacks necessary permissions to access volumes or registry keys.

Third-Party Conflicts: Other backup software or security agents (e.g., Sentinel Agent, as seen in similar cases) interfere with VSS.

if any service is stopped, start it. If it fails to start, check Event Viewer for errors under Applications and Services Logs > Microsoft > Windows > VSS.

Note: While setting VSS to Automatic is sometimes recommended, Manual is the default for Server 2022 and should suffice unless persistent issues occur.

Ensure no other backup applications (e.g., Veeam, BackupAssist) are running, as they can lock VSS resources, causing conflicts

Since you’ve confirmed the SAN Policy is Online All, ensure the disk hosting the backup target (and the system volume) has sufficient free space. Low disk space can cause VSS failures (e.g., Event ID 8193)

Recommendations

• Avoid Multiple Backup Tools: Ensure no other backup software is running, as conflicts are common.
• Update MARS Agent: Ensure you’re using the latest MARS agent version (check the Azure portal or Microsoft Download Center).

I hope this helps. Let me know if you have any further questions or need additional assistance.

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