opendataloader-project/opendataloader-pdf · error · IOException

pdf2img RESULT is empty

Error message

pdf2img RESULT is empty

What it means

fetchPageImage parsed the response JSON but the top-level RESULT field is missing, not an array, or empty. The code navigates RESULT[0].RESULT.PAGE_PNG_DATA, so a missing/empty RESULT array means the backend did not return a page render. 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:700

            .url(baseUrl + PDF2IMG_ENDPOINT)
            .post(body)
            .build();

        try (Response response = httpClient.newCall(httpRequest).execute()) {
            if (!response.isSuccessful()) {
                throw new IOException("pdf2img returned HTTP " + response.code());
            }

            ResponseBody respBody = response.body();
            if (respBody == null) {
                throw new IOException("pdf2img returned empty body");
            }

            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) {

View on GitHub (pinned to a7789b8e77)

Solutions

1. Log the raw pdf2img response body to see the actual envelope (often a SUCCESS=false with MSG)
2. Check the backend logs for the failing PAGE_INDEX
3. Retry the page; if consistent, accept the per-page skip
4. Align client and backend pdf2img contract versions

try {
    return cache.getOrFetch(pageNum, idx -> client.fetchPageImage(pdf, idx, crop));
} catch (IOException e) {
    if (e.getMessage().startsWith("pdf2img RESULT is empty")) {
        log.warn("page {} produced no render result — backend may have rejected it", pageNum);
    }
    continue; // skip this page
}

When it happens

Trigger: objectMapper.readTree(body) succeeds but root.get("RESULT") is null, not a JsonNode array, or has size 0.

Common situations: Backend returned SUCCESS=false but fetchPageImage still got 2xx with an error envelope lacking RESULT; version skew changing the pdf2img response shape; backend partial failure on the requested PAGE_INDEX.

Related errors

• pdf2img returned empty body
• pdf2img inner RESULT is null
• pdf2img PAGE_PNG_DATA is empty
• 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/413c53aa4738ca1f. Report an issue: GitHub.