---
title: "PDF download error with NGINX as reverse proxy"
canonical_url: "https://www.nutrient.io/guides/document-engine/knowledge-base/unable-to-download-pdf-with-nginx-reverse-proxy/"
md_url: "https://www.nutrient.io/guides/document-engine/knowledge-base/unable-to-download-pdf-with-nginx-reverse-proxy.md"
last_updated: "2026-06-08T15:36:24.935Z"
description: "Learn how to resolve PDF download failures using NGINX as a reverse proxy by ensuring sanitized document titles."
---

# Fix PDF download issues with NGINX reverse proxy

When you're using [Nginx] as a reverse proxy in front of Document Engine, and PDF download using any available means ([Web SDK](https://www.nutrient.io/api/web/classes/NutrientViewer.Instance.html#exportpdf), Web UI, or [Server API](https://www.nutrient.io/api/reference/document-engine/upstream/#tag/Import-And-Export/operation/download-document-pdf)) fails, make sure that the title of the document doesn't contain special, non-printable characters, e.g. escape codes.

To check if you're running into this issue, check the following:

1. Does the download directly through Server, bypassing Nginx, works correctly?

2. Does the download for documents with ASCII title works correctly?

If the answer to both of these questions is "yes", then you're likely seeing this issue.

To circumvent this, you need to re-upload the PDF file and provide a sanitized document title.
You can pass a custom title on upload using the [Server API](https://www.nutrient.io/api/reference/document-engine/upstream/#tag/Documents/operation/upload-document).
---

## Related pages

- [hash_mismatch error](/guides/document-engine/knowledge-base/hash-mismatch-error.md)
- [Monitoring Document Engine](/guides/document-engine/knowledge-base/monitoring.md)
- [Remote document storage](/guides/document-engine/knowledge-base/remote-document-storage.md)
- [How to fix 'Unknown CA' SSL errors in document uploads](/guides/document-engine/knowledge-base/remote-url-certificates.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)