Using moov-io/ach v1.34.2, calling POST /files/create with an ACH text body (Content-Type: text/plain) returned 500 errors for both valid and invalid files. The bypass flags allowMissingFileHeader=true and allowMissingFileControl=true in the query string had no effect. Submitting the same file as JSON worked fine, so the bug was specific to the raw NACHA text path.