Indexing into enumField with unknown value provides error with value but not which field

I am indexing 20M documents and using several dozen enumFields. Occasionally I'll hit the error

Solr add exception: Error from server at http://sr208:8983/solr/demog_dlx-160413_shard15_replica2: Unknown value for enum field: A

With no indication of which field this is part of it is very difficult to easily fix the problem. This error message should indicate both field and offending value.