# Groq route intermittently returns json_validate_failed with strict structured outputs

> Source: <https://discuss.huggingface.co/t/groq-route-intermittently-returns-json-validate-failed-with-strict-structured-outputs/179097#post_1>
> Published: 2026-08-21 20:36:52+00:00

Hi Hugging Face team,

We are seeing reproducible HTTP 400 failures through Hugging Face Inference Providers on the exact route:

`openai/gpt-oss-20b:groq`

The workload uses strict structured outputs for a deterministic entity-matching classification. The inputs are public and non-personal. We ran bounded diagnostics without retries, prompt tuning, or fixture changes.

Every failed call returned:

`invalid_request_error`

`json_validate_failed`

`structured_generation_failed`

Five repetitions per conservative `review`

fixture:

`entity-review-01`

: 0/5 successful`entity-review-02`

: 1/5 successfulThe one successful response matched the expected decision and confidence exactly. The same 188-byte strict output schema succeeded on a comparator. Request sizes were similar, so schema shape and request size do not explain the fixture-specific failures.

Failed request IDs for `entity-review-01`

:

`req_01m0jacw8zemabfp437wn7hdt8`

`req_01m0jacwxjeeva9k8rd84gc3pj`

`req_01m0jacxdne98r2akb1janc4w8`

`req_01m0jacy5qep39padbzhy7tzsp`

`req_01m0jacyw4eqvrhwd1p4b0pfak`

Failed request IDs for `entity-review-02`

:

`req_01m0jad0rvedvva48h0mg0h4qk`

`req_01m0jad1dse1zsj83nvcjb40yd`

`req_01m0jad2fcexc89hmwe2p34arb`

`req_01m0jad329en9s172f1vrcqrvg`

We then kept the prompt and inputs unchanged but replaced the response schema in memory with singleton enums requiring the already-checked output: `match=review`

, `confidence=low`

.

Results across three repetitions per fixture:

`entity-review-01`

: 3/3 successful`entity-review-02`

: 2/3 successfulThe remaining failure had the same fingerprint even though the model had no enum choice:

`req_01m0jzsav8e71rdt2j9qc4k27m`

This suggests enum selection contributes materially, but does not fully explain the route-level structured-generation failures.

Could you please confirm:

`json_validate_failed`

originated (HF router validation, provider validation, or generation)?`openai/gpt-oss-20b:groq`

has a known reliability limitation with strict JSON-schema outputs?The evidence is stored in a private repository, so the complete reproducible record is included here instead of linking to inaccessible CI pages.

Normal-schema targeted diagnostic:

`95c970d8f66979413bed18b680b86cfeeeec8780`

`32490428886`

`hf-benchmark-report-32490428886`

(artifact `9449532403`

)`sha256:c04babef1bb956d0b6f3633887521fbe6583d1e805bd85407dd998250ba1d7ef`

`1.3.0`

Forced-singleton-schema diagnostic:

`49ea63697f5afb82cccad93294ed858770c93232`

`32523118374`

`hf-benchmark-report-32523118374`

(artifact `9461257213`

)`sha256:da529cd0ef0fd601b9cae7dc948b72acdc6d3ce1ccf5be3f3ce1ffc0a486a769`

`1.4.0`

Both diagnostics used the same policy (`phase-12-2-hugging-face-public-evaluation-v1`

), registry (`hugging-face-structured-evaluation@1.1.0`

), and fixtures (`public-business-controlled-ai-v1@1.0.0`

). Raw prompts, inputs, outputs, provider messages, failed generations, and credentials were not retained. Authority leakage was zero.