The certificates do out-date, different from the business ones they expire in 1 to 2 years, so all signed document present very often "problems with the validation", you should change they way the errors are handle, since a not changed document, legally signed in the time period of the signature, is a complete different story from a changed document, or not valid signature.

Once again all signed documents will have expired signature, and it does not really mean there is an issue, just a new signature.