Mistral OCR rejects valid PDFs: `document_parser_invalid_file` (error 3740)
Yes, this was a Mistral-side bug, not your file. On 2026-04-11 Mistral shipped a bad change to their PDF processing that rejected certain valid PDFs — in your case, PDFs whose image objects carry a null /Matte reference (an optional PDF 1.7 compositing hint most parsers ignore silently). Mistral first rolled back pa…
Problem outcome: unknown