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WhisperX transcription error #17
Description
An HTTP 422 Unprocessable Entity error means your WhisperX server received your request but couldn't process it. This usually happens due to missing parameters, invalid audio formats, or data types that the server's API doesn't support.
reported by @MajorMokoto
Activity
fix: don't claim "Copied" when nothing was; correct a comment that ou…
topkoa commentedon Jul 14, 2026
Fixed — in both halves, and it turned out to be worse than a bad request: remote transcription had never worked for anyone.
transcribe_vocals_remote()was posting the vocal stem to/align, which is forced alignment — "here are the lyrics, tell me when each word is sung". Itstextfield is required and we have no lyrics (producing them is the entire point), so FastAPI rejected every request with a 422 in its validation layer, before the server's handler ever ran. There was no/transcribeendpoint at all. Not a regression: the feature was wired to an endpoint that answers a different question.What landed
POST /transcribe. Whisper hears the words, then wav2vec2 force-aligns Whisper's own transcript, so the timings are tight enough for a chart (raw Whisper segments drift, and a chart built from them sits visibly late).languagewas sent as a query param where the server reads a form field, so an explicit language hint was silently ignored and Whisper's auto-detection quietly decided instead — loading the wrong wav2vec2 aligner. It "worked", it was just wrong.To pick it up
The server's
server.pyis downloaded at install time, so an existing install needs to refresh its source: Settings → Stem Splitter → Check for update (the button added in plugin 0.3.3). Nothing large is re-downloaded — it's a few hundred KB of source, and the model cache is untouched. A server that hasn't updated now answers 404, and the plugin says so explicitly ("it predates remote transcription support") rather than failing silently.Why it hid for so long
Every test of that module tested the mapper, fed a hand-written dict. The mapper was always fine — the request was never exercised, and the request was the bug. Both repos now test the request itself, against a real FastAPI app, because the 422 happened above the handler: a unit test calling the handler directly would have passed while the endpoint rejected every call.
And the 422 explaining all this was reaching the app the whole time — it was being truncated into invisibility in the queue, which is what #16 was about. Fixing that is what made this findable.
feat: POST /transcribe — transcribe sung audio to word-level timed ly…