‘Unknown CA’ and Other SSL Certificate Issues When Adding a Document from a URL


PSPDFKit Server has been deprecated and replaced by PSPDFKit Document Engine. All PSPDFKit Server and PSPDFKit for Web Server-Backed licenses will work as before and be supported until 15 May 2024 (we will contact you about license migration). To start using Document Engine, refer to the migration guide. With Document Engine, you’ll have access to robust new capabilities (read the blog for more information).

Question: What to do when I can’t upload document from a URL because of the ‘Unknown CA’ error or other issues related to SSL certificates?


In order to upload a document from a URL, PSPDFKit Server needs to make an HTTP request to fetch it from the given server. It’s unable to complete this request due to invalid, expired, or malformed SSL certificates.

The most common issues related to the certificates are:

  • certificate is expired

  • certificates in a chain are not ordered correctly

If you encounter issues related to SSL certificates, we recommend checking your certificates with SSL Labs online tool: https://www.ssllabs.com/ssltest/. Also, you can read about best practices when it comes to deploying and managing SSL certificates in this guide: https://github.com/ssllabs/research/wiki/SSL-and-TLS-Deployment-Best-Practices.