Software⏱️ 2 min read📅 2026-06-03

How to Fix: SSL: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch

SSL certificate error due to private key mismatch. Check the private key file path and ensure it matches the certificate file.

Quick Answer: Verify that the private key file path in nginx.conf matches the location of your SSL.key file.

The 'SSL: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch' error typically occurs when the private key used for SSL/TLS encryption does not match the format or content of the associated certificate. This is a common issue with certificates issued by third-party Certificate Authorities (CAs) like StartSSL.

🛑 Root Causes of the Error

  • Incorrect private key format or encoding;
  • Private key not in PEM format;
  • Certificate and private key not signed by the same CA;

🔧 Proven Troubleshooting Steps

Method 1: Verify Private Key Format and Encoding

  1. Step 1: Open the private key file in a text editor to verify its contents.
  2. Step 2: Check if the private key is encoded in PEM format. If not, convert it using tools like OpenSSL.

Method 2: Use OpenSSL to Generate a New Private Key

  1. Step 1: Open a terminal and run the command `openssl genrsa -out /etc/nginx/conf.d/ssl/ssl.key 2048` to generate a new private key.
  2. Step 2: Copy the generated private key file to the correct location specified in your Nginx configuration.

✨ Wrapping Up

By following these steps, you should be able to resolve the 'SSL: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch' error and successfully configure your Nginx server with SSL/TLS encryption.

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