The upload dialog has always offered seven categories — certificate, manifest, report, permit, correspondence, photograph, other. The database, however, accepted any text at all, and its own starting value was general, which was never one of the seven and which the register had no label for.
Nothing you could do through the interface produced such a document. But anything arriving by another route — an import, a bulk load, a future connection to another system — could store a category the register could only show as a raw word, and grouping documents by category meant grouping over a set with no edges.
The seven are now the only categories the database will accept, and a document created without one is filed as other rather than as a value that does not exist.
No existing document was affected. The one document held was already filed correctly.