---
title: "Document Engine: hash_mismatch error"
canonical_url: "https://www.nutrient.io/guides/document-engine/knowledge-base/hash-mismatch-error/"
md_url: "https://www.nutrient.io/guides/document-engine/knowledge-base/hash-mismatch-error.md"
last_updated: "2026-05-14T21:57:26.840Z"
description: "Learn what the `hash_mismatch` error means in Nutrient and how to ensure your uploaded document URLs return the same file to prevent issues."
---

# hash_mismatch error

Question: What does the `hash_mismatch` error response mean?

Answer:

When you [upload documents from a URL](https://www.nutrient.io/api/reference/document-engine/upstream/#tag/Documents/operation/upload-document), Document Engine calculates SHA256 hash of its contents and stores it in the database. Since the file is stored in your infrastructure, Document Engine fetches it when necessary, e.g. in order to render it for viewing. When the fetched document's SHA256 doesn't match the hash that was stored on upload, a `hash_mismatch` error is returned.

To prevent this error, you must make sure that the URL you provided on upload always returns the exact same file.
---

## Related pages

- [Monitoring Document Engine](/guides/document-engine/knowledge-base/monitoring.md)
- [How to fix 'Unknown CA' SSL errors in document uploads](/guides/document-engine/knowledge-base/remote-url-certificates.md)
- [Remote document storage](/guides/document-engine/knowledge-base/remote-document-storage.md)
- [Signing service not available](/guides/document-engine/knowledge-base/signing-service-not-available.md)
- [How to convert an XLSM file to PDF using Document Engine](/guides/document-engine/knowledge-base/xlsm-to-pdf-conversion.md)
- [Fix PDF download issues with NGINX reverse proxy](/guides/document-engine/knowledge-base/unable-to-download-pdf-with-nginx-reverse-proxy.md)