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WorkaroundLast checked LangChain#parsing

Parser fails when the model wraps JSON in ```JSON instead of ```json

parse_json_markdown raises on output that is valid JSON inside a code fence.

Difficulty
Easy
Time
~5 min
Steps
2
Fixed in
—
Last checked
2026-10-15

No upstream fix: these steps work around it. Source: issue closed (not planned) without a merged fix. Last checked 2026-10-15.

Symptom

parse_json_markdown raises on output that is valid JSON inside a code fence.

Evidence what you'll see

  • The fence tag is uppercase JSON

Cause

The fence-matching pattern is case-sensitive.

Fix steps

0 of 2 done

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Verify the fix worked

  • Both ```json and ```JSON fences parse.
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Sources and credit

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