SSL connection errors may pop up unexpectedly in any browser, and Firefox isn’t an exception. Most of the time, the issue is a wrong SSL certificate configuration on the server site. If you load your website and see the SSL_ERROR_RX_RECORD_TOO_LONG message, it’s time to investigate.

RX Record Too Long

The first thing you should do is scan your SSL certificate for potential errors and vulnerabilities to confirm the problem. You can use a free SSL tool or enter the following OpenSSL command:

openssl s_client -connect domain.tld:*port*

If the error exists, you’ll receive the following output:

error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol:s23_clnt.c:766:

It says that while the connection is successful, the SSL handshake failed because no properly configured SSL certificate was found for this port. To solve this problem, try one of our solutions below:

Check Port 443 on your server-side

SSL installation can be a tricky process, especially for inexperienced users. Each server has its own rules and policies for managing SSL, so if you’ve missed or skipped a step, don’t worry, you’re not alone. 

Some systems require you to manually configure your website to load over Port 443 – the standard HTTPS port for all secured communications. To check whether your port is open or not, you’ll need your website’s IP address. You can find it via the DNS Checker by entering your domain name and selecting the A record.

DNS Checker

Once you know your IP address, use Portchecker to see if port 443 is open or closed. Enter your website’s IP address and click check. An open port means that something else causes the SSL_ERROR_RX_RECORD_TOO_LONG. However, if the port is closed, you’ll need to enable it manually from your server-side. Contact your hosting provider or ask a sysadmin for help.

Port Checker

Upgrade your TLS version

An old TLS protocol can also trigger this error. Today, most websites use TLS 1.2 and TLS 1.3 protocols to encrypt sensitive data online. If your server still supports the TLS 1.2 and TLS 1.3 protocol, disable the support as it may lead to a critical security breach.

Reset Firefox to default settings

If your SSL certificate is configured the right way, the problem may come from the browser. A quick fix can be a simple browser reset, and here’s how you can do it:

  • Type about:support in the address bar.
  • You will see a troubleshooting window.
  • Click on Refresh Firefox button and then confirm the refresh

Update Firefox

Another possible solution is to update your browsers to the latest and most secure version.

  • Click on the three horizontal lines on the top right-hand corner of your browser
  • Go to the Help section.
  • Click on About Firefox to see the current version of your browser. If an update is available, Mozilla will ask you to perform it.

Remove Extensions

Your browser extensions are meant to enhance your browsing experience, but sometimes they may come with a drawback. An incompatible extension can cause the SSL_ERROR_RX_RECORD_TOO_LONG issue, so when you’re faced with it, it’s always good practice to disable all your extensions for a while and see if the error disappears.

  • Navigate to Open Menu -> Add-Ons;
  • Click the disable button beside each extension
  • Restart the browser and check your website again

Clear Cache

A clogged cache can cause quite a few problems with your browser, and clearing it regularly will spare you from all sorts of errors and bugs.

  • Click the menu button and select Settings
  • Select the Privacy & Security panel.
  • In the Cookies and Site Data section, click Clear Data
  • Uncheck the Cookies and Site Data, so that only Cached Web Content is selected
  • Click Clear and close the settings window

Clear Firefox Cache

Disable Firefox Proxy

Check your proxy connection and disable it to see if the issue remains or not.

  • Double-click the Mozilla Firefox icon. 
  • In the Mozilla Firefox window, click on Tools > Options > Advanced
  • Click on the Network tab, then click on the Settings button.
  • In the Connection Settings window, make sure that the No Proxy option is selected.  
  • Click OK to apply the changes

Firefox Proxy

One of the above solutions should fix the SSL_ERROR_RX_RECORD_TOO_LONG issue, but if persists after you’ve tried every option, consider hiring a professional system engineer to get rid of it.

If you find any inaccuracies or have details to add to this SSL tutorial, please feel free to send us your feedback at [email protected] Your input would be greatly appreciated! Thank you.

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