Error Message following successful backup job

Although backup job is being reported as complete successfully, it always has the same error reported at the end:

2019-03-16 01:41:55 -03 - [Error-Duplicati.Library.Main.Operation.TestHandler-FailedToProcessFile]: Failed to process file

I have tried recreating the database but that didn’t resolve anything.
Not sure what to make of it, if someone could shed some light on what I should be checking that would be great.