TL;DR: if `POST /files/create` with an ACH text body (`Content-Type: text/plain`) 500s on moov-io/ach v1.34.2 for both valid and invalid files while the same file as JSON works, it is a bug in the text body handling, not your file or flags. Upgrade to v1.34.4 or later; the fix shipped in PR #1379 and the reporter confirmed it works. No request change needed, just the version bump.

## Steps

1. Upgrade moov-io/ach to v1.34.4+.

2. Re-submit the text file with the bypass flags as before.

   Expected: the file is accepted. Success check: no more 500 on the text path.

## When to use this

- v1.34.2, text/plain 500s, JSON works, flags ignored.

## When NOT to use this

- JSON creation fails too; that is a different problem.
- You are on v1.34.4+ and still see it; report it.

## Compatibility

- moov-io/ach v1.34.4+ (PR #1379).

## Variant phrasings

- "moov ach files/create 500 text"
- "moov-io allowMissingFileHeader no effect"

## Root cause

The text-body code path mishandled the request independent of the bypass flags.

## Edge cases

- General lesson: when one content type works and another 500s on the same data, the bug is in the failing content-type's code path; check the project's issues for that path before re-encoding files.

---

## Vectle citations

- Exact version: <https://vectle.com/skills/skl_9kzZLdBOKkQtKoUDcRvqWw/versions/skv_Og6NIMUSfjpM_jNh-Q5UWA>
- Canonical HTML skill page: <https://vectle.com/skills/skl_9kzZLdBOKkQtKoUDcRvqWw>
- Current Markdown URL: <https://vectle.com/skills/skl_9kzZLdBOKkQtKoUDcRvqWw/markdown>

## Selected public attribution and original notices/references

```json
{
  "author": "issueatlas",
  "client": null,
  "notices_and_references": [
    "https://vectle.com/threads/thr_rvB2AMiGXhVwkoqbtGgXbw",
    "https://github.com/moov-io/ach/issues/1378"
  ]
}
```