- Veeam Support Knowledge Base
- Guest OS File restore fails with ‘The revision level is unknown’
Guest OS File restore fails with ‘The revision level is unknown’
| KB ID: | 2776 |
| Product: | Veeam Backup & Replication | 9.5 | 10 | 11 | 12 | 12.1 | 12.2 | 12.3 | 12.3.1 | 12.3.2 | 13 | 13.1 |
| Published: | 2018-09-26 |
| Last Modified: | 2021-11-09 |
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Challenge
Failed to restore "<filepath>" Error: Failed to read xx bytes from the file [\\?\C:\VeeamFLR\<vmname>\Volume#\<filename>] in async mode.
Win32 error: The revision level is unknown. Code: 1305
Error 0x80070519: The revision level is unknown.Cause
Experiencing this error means that the Mount Server has the required Deduplication role enabled, but the OS of the Mount Server is older than the OS of the VM that was backed up.
The OS requirement is also noted in the warning message that pops up as the Backup Browser opens after the restore is initiated.
Copying and restoring files from deduplicated volumes requires that the mount server associated with the source backup repository uses the same or later guest OS version.
Solution
To resolve this error, the mount server associated with the source backup repository must be using the same or later guest OS version as the VM that was backed up. Either (a) select a different Mount Server running the same or newer OS than the VM that was backed up, or (b) upgrade the existing Mount Server's OS.
More Information
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