810D5A61-809F-49c2-BD75-177F0647D2BA is SEPC Iron Revocation List v12.1.
In your example download of delta for 810D5A61-809F-49c2-BD75-177F0647D2BA failed.
Second example shows - successful download of defs for 535CB6A4-441F-4e8a-A897-804CD859100E.
...those two are completely different monikers. Check further in the logs if you find any more entries for 810D5A61-809F-49c2-BD75-177F0647D2BA? If it was downloaded after this first failure it should be fine - but if it is failing all over again it my be some corruption of the definitions itself.