The case of an unrecoverable error in DPM 2012 SP1 UR3
The DPM error from a previous UR is back: "When using Data Protection Manager 2012 Service Pack 1 for tape backup, you receive the following error message: The operation failed due to an error in the protection agent.
One of the issues closed in Update Roll-Up 2 for System Center Data Protection Manager 2012 SP1 was the following:
Problem 5: When using Data Protection Manager 2012 Service Pack 1 for tape backup, you receive the following error message:
The operation failed due to an error in the protection agent. (ID 998 Details: The parameter is wrong (0x80070057))
So far, so good. This bug seems to pop up again and again and was basically introduced in DPM 2010 where you couldn't save too many items to tape, then it was fixed in a QFE, then it was back again until it was finally (or so we think) fixed in the update rollup mentioned above. So I found it very strange when I was confronted with this bug again, on a system running DPM 2012 SP1 UR3, more precisely, the second edition of UR3.
One of the data sources got stuck and would not be written to tape even after several retries. The only solution that finally worked was to dismiss the warning and create a manual tape-type restore point using another (later) disk restore point created while I was struggling with the warning.
So if you encounter a similar problem, try manually backing up your data source to tape from a different restore point than the one causing the error.