Software⏱️ 3 min read📅 2026-06-11

How to Fix: Can't connect to https on ubuntu - "Unknown SSL protocol error"

Troubleshooting guide for Ubuntu users experiencing issues connecting to a specific server over SSL.

Quick Answer: Check the server's SSL configuration and ensure that the correct CA certificates are used.

📋 Table of Contents

  1. ⚠️ Common Causes
  2. ✅ Best Solutions to Fix It
  3. ✨ Wrapping Up

The issue of being unable to connect to https on Ubuntu due to an 'Unknown SSL protocol error' affects users who rely on this functionality for their work or personal activities. This error can be frustrating, especially when other servers within the same domain are accessible.

This problem is not unique to the user and can affect anyone using Ubuntu with a specific server address that uses an outdated or unsupported SSL protocol.

⚠️ Common Causes

  • The primary reason for this issue is that the server in question may be using an outdated or unsupported SSL protocol, such as SSLv3. This protocol has been deprecated since 2014 and is no longer considered secure by modern browsers.
  • Another possible cause could be a configuration error on the Ubuntu server-side, where the SSL settings are not properly configured to support the latest security protocols.

✅ Best Solutions to Fix It

Update OpenSSL and configure the server to use the latest TLS protocol

  1. Step 1: Step 1: Update OpenSSL to ensure it has the latest security patches. This can be done by running the command `sudo apt-get update` followed by `sudo apt-get upgrade openssl`. Wait for the package to finish updating and upgrading.
  2. Step 2: Step 2: Configure the server to use the latest TLS protocol by editing the `/etc/ssl/openssl.cnf` file and setting the `DEFAULT_SSL_CIPHER` variable to a value that includes the latest security protocols, such as 'ECDHE+AES256:EDH+AES256'.
  3. Step 3: Step 3: Restart the OpenSSL service to apply the changes. Run the command `sudo service openssl restart`.

Check the server configuration and update the SSL settings manually

  1. Step 1: Step 1: Check the server's SSL settings by running the command `openssl s_client -connect powerschool.spokaneschools.org:443`. Look for any outdated or unsupported protocols in the output.
  2. Step 2: Step 2: Update the SSL settings manually by editing the `/etc/ssl/openssl.cnf` file and setting the `DEFAULT_SSL_CIPHER` variable to a value that includes the latest security protocols. Refer to the OpenSSL documentation for more information on valid cipher values.

✨ Wrapping Up

To resolve this issue, it is recommended to update OpenSSL and configure the server to use the latest TLS protocol. If the server configuration is not updated manually, an alternative solution involves checking the server's SSL settings and updating them to include the latest security protocols. By following these steps, users should be able to connect to https on Ubuntu without encountering the 'Unknown SSL protocol error'.

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