If PDFShift returns 422 invalid HTML, capture the complete response body and check both the request and the source you sent. PDFShift’s published examples document a v3 conversion request with a source value containing either raw HTML or a URL, but they do not define this exact error message or establish one definitive cause. Diagnose from the response payload rather than assuming the markup is malformed.
1. Capture the full error before changing the request
Record the HTTP status and response body for the failed request. A status-only log discards information that may distinguish a request-validation problem from a source-loading failure. PDFShift’s Python examples check unsuccessful responses and expose the response text or content; its aiohttp guide likewise recommends handling error details and notes that an error response does not contain a PDF. See PDFShift’s Python guide and aiohttp guide.
Do not log an API key or sensitive document content. If the body itself may contain private data, redact it before sharing or retaining it. Preserve enough sanitized detail to compare failing and successful requests.
2. Verify the documented request envelope
PDFShift’s v3 conversion endpoint is https://api.pdfshift.io/v3/convert/pdf. Its examples use a POST request with a JSON body containing source; that value can be raw HTML or a URL. Check that your client is sending the intended endpoint, method, JSON body, and source field, and that its API-key configuration is correct for the client or workflow. These checks validate the documented request shape; they do not establish that any particular mismatch causes this exact 422. See PDFShift’s API guides and PDFShift.
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3. Identify which source path you are using
Raw HTML source
Confirm that the application passes the complete generated HTML as a JSON string—not as a separately concatenated or incorrectly escaped fragment. Use a JSON encoder rather than manually escaping quotation marks, backslashes, or newlines. Inspect the final serialized request body with secrets and sensitive content removed. A minimal HTML document can help determine whether the problem appears only after your template or assets are added.
URL source
Check whether the page is reachable by the conversion service, not merely by your own browser. Look for login requirements, private routes, access controls, redirects, or other conditions that prevent an external service from retrieving it. PDFShift documents a raise_for_status option for treating an unsuccessful remote-source response as a conversion failure; consult its Python guide for the relevant client example.
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Raw HTML and URL input are distinct diagnostic paths. For raw HTML, inspect the generated markup and JSON encoding. For a URL, investigate remote retrieval and page access. Do not assume that using a particular programming language is itself the cause.
4. Reduce external dependencies and isolate the failing part
PDFShift recommends avoiding unnecessary network requests during conversion. Its help guidance suggests sending raw HTML, inlining CSS and JavaScript where practical, removing unnecessary scripts, considering base64 image data, and optimizing image sizes. These measures reduce external dependencies and can simplify diagnosis; PDFShift does not document them as guaranteed fixes for this exact 422. Read PDFShift Help Center’s conversion-time advice, which says, “Generally speaking, avoid any network requests.”
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- Try a small valid HTML document using the documented raw-HTML input mode.
- Add your application-generated template and compare the complete sanitized response.
- Reintroduce scripts, stylesheets, fonts, and images in stages, checking the result after each change.
- If using a URL source, test a page that is publicly reachable and remove access restrictions only where appropriate for your security requirements.
This staged test is a diagnostic technique, not a published PDFShift remedy for the exact message. Keep the request and response details for each case so you can identify what changed.
5. Common symptoms and what to check
| What you observe | What to inspect | Next step |
|---|---|---|
| The log shows only “422” | The response body was discarded or never logged. | Capture the full response content safely before retrying. |
| The source is raw HTML | The final HTML string, JSON encoding, and the presence of the expected source field. |
Try a minimal document, then add generated content and assets incrementally. |
| The source is a URL | Reachability from the conversion service, authentication, route access, and redirects. | Test an accessible URL or use raw HTML to separate retrieval from markup concerns. |
| The response remains ambiguous | The sanitized response body and a minimal reproducible request. | Send those details to PDFShift support and ask what condition triggers the exact message. |
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Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Frequently Asked Questions
Does HTTP 422 prove that my HTML is malformed?
No. The available PDFShift documentation does not define this exact error phrase or confirm a single cause. Use the response body and request details, and ask PDFShift support if those do not identify the condition.
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Test the input mode your integration actually uses. If you need to separate remote-page retrieval from HTML handling, compare with a minimal raw-HTML request.
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