Maureen Cresci Callahan, Head of Archives & Special Collections at UConn, has been working with a team to do a search-and-destroy on XML errors (usually the result of mixed content inserted into finding aids), which cause ArchivesSpaces’ pdf export to fail. You can try out their tool here: https://github.com/meau/ASpaceBadXML
Thanks to Maureen!
Connecticut's Archives Online