How a Silent OCR Bug Returned Blank PDFs While Appearing to Succeed

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A web-based OCR tool spent months producing searchable PDFs that contained no actual text, with every stage of failure masked by code that swallowed errors silently. A resolution-dependent canvas crash in pdf.js went undetected because it only triggered above a certain image size threshold, making it invisible during low-resolution testing. A renamed data field in tesseract.js v7 was read through a fallback that treated an undefined value as an empty result, while a required output flag defaulted to null rather than signalling it was missing. Unsupported characters in six of twelve languages caused per-word encoding exceptions that were caught and discarded, leaving pages wordless but clean. An error classifier then misread an internal crash message as a file-corruption warning, incorrectly telling users their own PDFs were damaged.

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ProgrammingDEV Community ·

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