It is common to encounter the SSL_ERROR_RX_RECORD_TOO_LONG error on Firefox when browsing to a website using https protocol - incorrect SSL (Secure Sockets Layer) configuration is the most common cause. However, a new release of TLS (Transport Layer Security) or your antivirus program may also be contributing factors in a handful of cases.


The reason behind this firefox error is due to improper configuration of SSL certificate. A client wants to connect to an opened port on the server but the SSL certificate is not installed properly. So, it shows that the connection has been made but the SSL certificate is not properly configured. The wrong configuration of the SSL certificate on the webserver is the most common cause of this error.


How to fixing SSL_ERROR_RX_RECORD_TOO_LONG Firefox error?

Here are the measures you can take on fixing the SSL_ERROR_RX_RECORD_TOO_LONG Firefox error:

1.   Switch to HTTP from HTTPs

The first thing you should try is to bypass the security layer provided by HTTPs and connect on the plain old HTTP. See if you can connect to the website by replacing https:// with http://

Note that this is not a permanent solution and makes you vulnerable to hacking, so use it only till a permanent fix to the issue is available.

2.   Use “no proxy” setting

This problem may also be caused due to incorrect proxy settings – try disabling your proxy settings to see if the problem goes away.

  • Go the menu and select “Options”.
  • Scroll down and click on “Settings” in the “Network Settings” section.

Network Setting

  • Select “No proxy” and click on “OK” Restart Firefox when done and reload the website.

No Proxy

3.   Open browser in safe mode

Opening Firefox in Safe mode switches off hardware acceleration and browser add-ons - this may help fix the error.

  • Select ”Restart with Add-ons Disabled” from the Help menu.

Restart Addons Disabled

  • Click on “Start in Safe Mode” on the next pop up.

Start In Safe Mode

  • Now reload the site to see if this works.

4.    Switch off browser add-ons

If you can open the website using Safe mode, you may want to try switching off the add-ons and disable them one at a time to see if an add-on causes the problem.

  • If you are still in Safe mode, come out of it by navigating to Help -> ”Restart with Add-ons Enabled” menu item.
  • Type about:addons in the address bar and press Enter.
  • Disable the add-ons one at a time to see if any one of those was causing the problem showing as in below image.

5.   Refresh the browser

Refreshing Firefox will restore default settings is an effective way of fixing most browser issues. However, this will undo all the settings you’ve made in Firefox and remove all add-ons and themes.

  • To do so, select Help>> “Restart with Add-ons Disabled” from the menu.

Restart Addons Disabled

  • Click on “Refresh Firefox” on the next pop up and see if this will fix SSL_ERROR_RX_RECORD_TOO_LONG Firefox warning.

6.   Update Firefox to the latest release

You may be able to fix this Firefox warning only by updating your browser to the latest version.

  • Go the menu and select “Options
  • Scroll down to the “Firefox updates” section.

Firefox Is Up to date

  • Make sure your browser is updated to the latest release, if not then click on 'Check for Updates' option to update fireforx.

7.   Clear Cache

You can clear cache and fix this issue. Even, you need to browse in incognito mode or private window in browser to stay away from cache. You can use below command to clear cache to reload a webpage.

  • Ctrl + Shift + R
  • Shift + click Reload

8.   Upgrade TLS Version

Mostly browsers including Mozilla are withdrawing support to TLS 1.0 and they now prefer to TLS 1.2 and 1.3 version. If you are using older version, then it is time to update your TLS version from 1 to 3 in your SSL/TLS library. Even, OpenSSL has also started to support TLS1.3 version.

9.   Buy an SSL certificate and configure it properly

Eventually, the fix must be made on the webserver in most cases. Buy SSL certificate and configure it properly, so your end-users do not have to deal with temporary solutions to fix this Firefox warning.

As you can well see, the SSL_ERROR_RX_RECORD_TOO_LONG Firefox error can be frustrating for the end-users. There are things you can try on the browser to fix the problem in some cases. In a few instances, disabling antivirus programs and TLS security settings on the browser may also help circumvent the problem. However, in most situations, you must buy an SSL certificate of a top SSL providers and configure it properly on your webserver to provide a seamless and secure experience to your customers. Hope these tips help you deal with this problem.