---
title: "PDF digital signature troubleshooting | Nutrient"
canonical_url: "https://www.nutrient.io/guides/web/signatures/digital-signatures/troubleshooting/"
md_url: "https://www.nutrient.io/guides/web/signatures/digital-signatures/troubleshooting.md"
last_updated: "2026-05-15T09:08:03.712Z"
description: "Discover solutions for digital signature issues and enhance your document signing experience with our expert troubleshooting tips."
---

# Troubleshoot common digital signature issues

Troubleshoot common issues you might encounter when setting up digital signatures.

- [Can I modify a document after it is digitally signed?](https://www.nutrient.io/../troubleshooting/document-modified-since-signature/)

- [The produced digital signature isn’t valid, and the validation status says “the document has been tampered with”](https://www.nutrient.io/../troubleshooting/invalid-signatures/)

- [The validation status of a digital signature says that “at least one signature has problems”](https://www.nutrient.io/../troubleshooting/chain-of-certs-not-valid/)

## Common mistakes

| Mistake                                                  | Symptom                             | Fix                                                                   |
| -------------------------------------------------------- | ----------------------------------- | --------------------------------------------------------------------- |
| Using a self-signed certificate in production            | Yellow warning bar in Adobe Reader  | Use an AATL-trusted certificate                                       |
| Missing certificate chain                                | “Certificate chain not valid” error | Include intermediate certificates in signing response                 |
| Wrong signature format (PKCS#1 vs PKCS#7)                | “Invalid signature” after signing   | Check your HSM/signing service output format matches SDK expectations |

| Signing already-signed document without incremental save | Previous signatures invalidated     | Use incremental saving mode                                           |
| Certificate expired                                      | Signature shows as invalid          | Renew certificate before expiry                                       |
---

## Related pages

- [Digital signature architecture](/guides/web/signatures/digital-signatures/architectures.md)
- [Understanding digital signatures and their importance](/guides/web/signatures/digital-signatures/overview.md)
- [Understanding PAdES and CAdES digital signatures](/guides/web/signatures/digital-signatures/standards.md)
- [Supported cryptographic formats](/guides/web/digital-signatures/introduction-to-digital-signatures.md)

## Pages in this section

- [Understanding digital signature validation statuses](/guides/web/signatures/digital-signatures/troubleshooting/chain-of-certs-not-valid.md)
- [Document Modified Since Signature](/guides/web/signatures/digital-signatures/troubleshooting/document-modified-since-signature.md)
- [Invalid Signatures](/guides/web/signatures/digital-signatures/troubleshooting/invalid-signatures.md)