Software⏱️ 3 min read📅 2026-06-15

How to Fix: Tomcat SSL error after setting up certificate

Learn how to fix: Tomcat SSL error after setting up certificate.

Quick Answer: Try checking your system settings or restarting.

📋 Table of Contents

  1. 🔍 Why This Happens
  2. ✅ Best Solutions to Fix It
  3. 💡 Conclusion

The error 'This site can’t provide a secure connection localhost sent an invalid response.' occurs when a user attempts to access a web application over HTTPS but receives an invalid SSL certificate. This issue affects users who have set up Tomcat with SSL encryption on Ubuntu 16.04 and are trying to connect to the server using HTTPS.

This error is frustrating because it prevents users from accessing the web application securely, which can compromise sensitive data transmission. In this guide, we will walk through the steps to troubleshoot and resolve this issue.

🔍 Why This Happens

  • The primary reason for this error is that the SSL certificate generated using OpenSSL may not be properly configured in Tomcat. This can happen if the certificate file path or key file path are not correctly specified in the server.xml file.
  • An alternative reason could be that the SSL protocol version used by Tomcat does not match the one expected by the client browser.

✅ Best Solutions to Fix It

Verify Certificate File Path and Key File Path

  1. Step 1: Check if the certificate file path and key file path in the server.xml file are correct. Ensure that the paths are absolute or relative to a specific directory (e.g., conf/). If not, update the paths accordingly.
  2. Step 2: Verify that the SSLCertificateFile attribute points to the correct certificate file (cert.pem) and the SSLCertificateKeyFile attribute points to the correct key file (key.pem).
  3. Step 3: If using a keystore, ensure it is correctly configured in Tomcat. You can do this by adding the following line to the server.xml file:

Update SSL Protocol Version

  1. Step 1: Check the sslProtocol attribute in the Connector element. Ensure that it is set to 'TLS' (or a compatible version).
  2. Step 2: Try updating the sslProtocol attribute to include more secure protocols, such as 'TLSv1.2' or 'TLSv1.3'. However, be aware that this may break compatibility with older browsers.
  3. Step 3: If you are using an older browser, consider downgrading your Tomcat version or providing a fallback for older browsers.

💡 Conclusion

To resolve the SSL error in Tomcat, verify that the certificate file path and key file path are correctly specified in the server.xml file. Additionally, ensure that the sslProtocol attribute is set to 'TLS' (or a compatible version) to match the expected protocol version by the client browser. By following these steps, you should be able to resolve the issue and access your web application securely over HTTPS.

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