I have a nightly scheduled backup on my server running Server 2012 R2. Every time, the backup of Hyper-V (including my one VM) fails. The error wbadmin gives me is "The component <Name of the VM>(Online) was skipped during the snapshot and will not be available for recovery. Error: The writer experienced a non-transient error. If the backup process is retried, the error is likely to reoccur."
In event viewer, SPP throws an Event 16387, saying "Writer Microsoft Hyper-V VSS Writer experienced some error during snapshot creation. More info: ." (copied just as it was written, that's not a typo). Details say "The writer experienced a partial failure. Check the component level error state for more information. (0x80042336) Unspecified error (0x80004005)".
What could be causing this problem?