How to Fix The SSL_Error_RX_Record_Too_Long Firefox Error

Firefox remains a popular internet browser for close to 153 million people. If you’re one of these million that chooses to use Firefox as your primary browser, then a common error you may come across is the SSL_Error_RX_Record_Too_Long Firefox error. Whether you are a website admin or a regular Firefox user, we’re going to give you tried and tested solutions on how to fix this authentication error. 

What does the SSL_Error_RX_Record_Too_Long error mean?

The SSL_Error_RX_Record_Too_Long is a Mozilla Firefox authentication error that typically occurs when an SSL certificate is misconfigured on the server-side. It means that even if the server’s listening port is open, you will not be able to connect to the server properly as the secure data cannot be verified. The reason for this is that the SSL certificate isn’t working correctly. 

Additionally, there are two common root causes on the client-side why you may see the SSL_Error_RX_Record_Too_Long appearing:

• You are not using TLS 1.3 or haven’t updated your SSL/TLS library. 
• You are using an irregular server port, or your listening port is misconfigured. 

There are some other issues that can cause the SSL_Error_RX_Record_Too_Long Firefox error on the client-side, but these two are the most common. 

Proven fixes to the SSL_Error_RX_Record_Too_Long error for web administrators

If you’re not already using TLS 1.3, you definitely should be. Formally rolled out across the web in August 2018, TLS 1.3 is the long-awaited successor of TLS 1.2, improving web security, performance, and efficiency. It simplifies the Transport Layer Security handshake by only using one round trip rather than the two that it took with TLS 1.2, ensuring that encrypted communications across the web are faster and more secure.  

1. Upgrade your TLS version

When TLS 1.2 first came out, Firefox had the exact same issue with the SSL_Error_RX_Record_Too_Long occurring. So, if you’ve just upgraded to TLS 1.3, this may be the reason that you’re seeing this error pop up. The key here is to ensure that your Open SSL/TLS library is updated to the latest version to support TLS 1.3.

If you are not using TLS 1.3 yet, and aren’t planning on doing so until further down the line, then it is recommended that you have at least TLS 1.2 installed. If you’re curious about how to do this on a Windows client, you can read about TLS 1.2 installation here, and 1.3 installation here. 

Note: If you are interested in learning more about TLS, please post a comment below to let us know.

2. Properly configure your listening port

If you use an irregular listening port, or you lack the trusted SSL certification layer on the listening port, then it’s likely what causes the SSL_Error_RX_Record_Too_Long Firefox error. You will need to configure it to port 443, which is the proper listening port for HTTPS-based traffic. 

If you know the type of server that you use, you can search for the exact method necessary to reconfigure your port. Simply perform a search for “Server Name + Port 443 + HTTPS” to configure it correctly. 

Here are a few examples: on an NGinX server, you would put “listen 443 SSL” and on an Apache (xamp) server, you would change the config file to read “listen 443 https” – just depends on what server you are using. 

Proven fixes to the SSL_Error_RX_Record_Too_Long error for end users 

Now, if you are a regular internet user who uses Firefox and receives the  SSL_Error_RX_Record_Too_Long error, there are a few things you can try to solve the issue on the client-side. Please keep in mind that this is primarily a server-side error, so the amount of success that you have may vary. 

1. Use incognito mode

In some cases, using incognito mode may allow you to get around the SSL_Error_RX_Record_Too_Long Firefox error. Just make sure that if you try this method, you are only logging into websites that have a working SSL certificate.

2. Consider using a VPN

If you are willing to go through the process of setting up a virtual private network (VPN), then you can get encrypted protection in the interim without needing to worry about the SSL_Error_RX_Record_Too_Long error. This isn’t a 100% reliable or guaranteed way, but it has worked for some users in the past. 

3. Update your Firefox browser

Another reason you may get the SSL_Error_RX_Record_Too_Long error is if your Firefox browser is out of date. To update it, you’ll want to:

1. First, open a new tab in Firefox.
2. Click on the Hamburger Menu in the top right-hand corner.

3. Choose the “Help” option and then choose About Firefox.

4. A little box will pop up that will tell you if there is an update.
5. If there is an update, install it and restart Firefox.

4. Disable all Firefox extensions

It is possible that new updates rolling out for some extensions may be interfering with your HTTPS protocol in Firefox. We recommend that you try disabling all extensions and refreshing Firefox to see if it makes a difference. To disable extensions:

6. Open a new tab in Firefox.
7. Click on the Hamburger Menu in the top right-hand corner.

8. Choose Settings from the list.
9. Click on Extensions/Themes in the bottom left-hand corner.
10. Under Extensions, you’ll see “enabled” – toggle these extensions off with the slider.

11. Restart Firefox completely.

5. Check your proxy settings within Firefox

Sometimes a misconfigured proxy setting can cause the SSL_Error_RX_Record_Too_Long Firefox error. While it is not recommended to completely disable the use of a proxy unless you are an IT admin and know what you are doing, we will provide the steps below. Take caution in using these steps.

1. Open a new tab in Firefox and head to Settings via the Hamburger Menu.

2. Under General Settings, scroll down until you see Network Settings.

3. Click on the Settings button.
4. In the new window that pops open, choose no proxy from the list and hit okay.

5. Restart Firefox.

6. Change the Security.TLS.Version.Max preference

It can happen that the website you are visiting supports TLS 1.3, but the operating system of your computer doesn’t. If this is the case, you will get the SSL_Error_RX_Record_Too_Long error when using Firefox. You can drop or change the security version support for TLS down a layer to 1.2 by doing the following:

1. In a new tab in Firefox, type in “about:config” and hit Enter.
2. Accept the warning prompt that appears.
3. In the search field, type in “TLS”.
4. Go down the list until you see security.tls.version.max. 
5. Here, you will want to change the number from 4 to 3.

By changing the number to 3, you are telling Firefox to use TLS 1.2.  Keep in mind though, that doing this may open you up to vulnerabilities, as most websites use TLS 1.3 nowadays. 

7. Reinstall Firefox

If none of the solutions above fixed the SSL_Error_RX_Record_Too_Long error, consider reinstalling Firefox completely. To remove it, you can either:

• Right-click Firefox on your desktop or in your start menu and choose uninstall.

• Open the Control Panel, choose Uninstall programs, and find Firefox in the list. Highlight it, and then choose to uninstall from the top of the window.

To reinstall Firefox, you will need to use another internet browser to search Mozilla Firefox and install it from their main page.

What you should NOT do as a regular user

1. Don’t switch to using HTTP

It may be tempting to simply switch the HTTPS:// with HTTP:// to get around the failed SSL certificate, but in doing so, you open yourself up to being attacked or having your information stolen. 

The problem with HTTP is that it is not designed to transmit data across the web securely, and it was created for the time when the internet was solely for sharing information. The reason it is no longer used is that sensitive data isn’t secured during TLS handshake when using HTTP. As a result, information like login credentials and financial transactions are not encrypted.

2. Don’t turn off your antivirus

While turning off your antivirus will stop it from fighting Firefox and the SSL_Error_RX_Record_Too_Long error, it also means that you are opening up your computer to being hacked.  

To just simply turn off your antivirus and surf the web without it enabled means that you could easily pick up viruses, malware, or spyware along the way. 

Conclusion: SSL_Error_RX_Record_Too_Long

If you are a regular Firefox user and are still getting the SSL_Error_RX_Record_Too_Long Firefox error even after trying all of the solutions above, then it would be prudent to contact the website owner to notify them of the error. 

In the interim, consider switching to another browser for your day-to-day surfing, as you’ll need to ensure that the SSL certificate is working correctly. After all, SSL allows you to communicate with websites safely without having your sensitive data compromised.