opendataloader-project/opendataloader-pdf · error · IOException

pdf2img PAGE_PNG_DATA is empty

Error message

pdf2img PAGE_PNG_DATA is empty

What it means

The nested RESULT object exists but PAGE_PNG_DATA is missing or an empty string, so there is no image payload to decode. fetchPageImage checks this before attempting Base64 decode. Per-page IOException, caught and logged by table/figure handlers.

Source

Thrown at java/opendataloader-pdf-core/src/main/java/org/opendataloader/pdf/hybrid/HancomAIClient.java:712

            }

            JsonNode root = objectMapper.readTree(respBody.string());
            // Navigate: RESULT[0].RESULT.PAGE_PNG_DATA
            JsonNode resultArr = root.get("RESULT");
            if (resultArr == null || !resultArr.isArray() || resultArr.size() == 0) {
                throw new IOException("pdf2img RESULT is empty");
            }

            JsonNode pageResult = resultArr.get(0);
            JsonNode innerResult = pageResult.get("RESULT");
            if (innerResult == null) {
                throw new IOException("pdf2img inner RESULT is null");
            }

            String pngBase64 = innerResult.has("PAGE_PNG_DATA")
                ? innerResult.get("PAGE_PNG_DATA").asText() : null;
            if (pngBase64 == null || pngBase64.isEmpty()) {
                throw new IOException("pdf2img PAGE_PNG_DATA is empty");
            }

            byte[] pngBytes;
            try {
                pngBytes = Base64.getDecoder().decode(pngBase64);
            } catch (IllegalArgumentException e) {
                // fetchPageImage is declared to throw IOException and callers catch
                // only IOException. Escaping IAE would abort the whole conversion
                // instead of skipping the failed page.
                throw new IOException("pdf2img PAGE_PNG_DATA is not valid Base64", e);
            }
            BufferedImage image = ImageIO.read(new ByteArrayInputStream(pngBytes));
            if (image == null) {
                throw new IOException("pdf2img PAGE_PNG_DATA is not a readable image");
            }
            if (cropOutput.active()) {
                savePageImageFile(cropOutput.directory(), pageIndex, pngBytes);
            }

View on GitHub (pinned to a7789b8e77)

Solutions

1. Check backend pdf2img logs for PNG encoding/storage errors on the page
2. Confirm the field name PAGE_PNG_DATA matches this backend version
3. Retry the page; if persistent, accept the per-page skip
4. Ensure the backend has disk/memory for page image encoding

try {
    return cache.getOrFetch(pageNum, idx -> client.fetchPageImage(pdf, idx, crop));
} catch (IOException e) {
    if (e.getMessage().contains("PAGE_PNG_DATA is empty")) {
        log.warn("page {} rendered but PNG payload missing", pageNum);
    }
    continue;
}

When it happens

Trigger: innerResult.has("PAGE_PNG_DATA") is false, or innerResult.get("PAGE_PNG_DATA").asText() is null or empty, inside fetchPageImage.

Common situations: Backend rendered the page but failed to encode/attach the PNG (disk full, encoder error); backend returned a placeholder entry without image data; backend version returning a renamed field.

Related errors

• pdf2img returned empty body
• pdf2img RESULT is empty
• pdf2img inner RESULT is null
• pdf2img PAGE_PNG_DATA is not valid Base64
• pdf2img returned HTTP %s

AI-assisted analysis of opendataloader-project/opendataloader-pdf@a7789b8e77 (2026-08-14). Data as JSON: /api/errors/85e099e1b86c68d7. Report an issue: GitHub.