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Over the years, Mozilla Firefox has proven itself to be a fast, lightweight, and reliable alternative to Google's own Chrome browser. While it's certainly a stellar tool and an excellent choice for any profile of user, the Firefox browser comes with its own set of error message alerts, warnings, and pop-ups that don't necessarily overlap with any other web browser. The infamous SSL_ERROR_RX_RECORD_TOO_LONG error, for example, is one such message, and if you're coming to Mozilla Firefox after years of experience with other web browsers, it may not be immediately apparent what it's all about.

To that end, we've prepared a short (but comprehensive) guide on how to best handle the SSL_ERROR_RX_RECORD_TOO_LONG error in Mozilla Firefox. On top of solutions, we also have a few key explanations to help you understand what causes these issues to crop up, why certain solutions may or may not work, and why some of them you may not even wish to try out in the first place.

So, if you find yourself facing ssl_error_rx_record_too_long and just can't figure out where to go from here, you're at the right place.

Everything You Need to Know About SSL_ERROR_RX_RECORD_TOO_LONG


SSL_ERROR_RX_RECORD_TOO_LONG is a Firefox error that will typically appear due to some manner of server-side misconfiguration. The good news is that fixing this issue usually won't be a huge time-sink on your end; the bad news is that oftentimes the end-user (i.e. website visitor) might not be able to fix the issue in the first place. Firefox users that would still like to give it their best shot and resolve this Firefox error if at all possible, however, do have a few options at their disposal.

It's worth pointing out right away that it is not recommended that users switch to HTTP browsing to resolve this issue. Doing so switches over from secure connections to a severely outdated security protocol that has way more potential for malicious party interference, turning your device into a bit of a sitting duck.

There are other ways to potentially fix SSL_ERROR_RX_RECORD_TOO_LONG, but disabling HTTPS is the last thing you should do. Consider this an absolute last resort, and consider the simple fact that a website that doesn't support HTTPS traffic might be a red flag in and of itself in the first place.

Is this an SSL certificate issue?

Indeed, it would appear that most instances of this particular issue relate to the TLS version of a website you may be attempting to access. If the website owner hasn't had the chance (or inclination) to update the site's SSL certificate, or if it's fully up-to-date but isn't a properly configured SSL certificate, visitors may get this error while using the Firefox browser.

Is it specific to the Mozilla Firefox browser?

This SSL certificate error is unique to Mozilla Firefox, in that other website browsers generally have their own variations of this same error message. Expect to see a "Secure Connection Failed" or some equivalent thereof if you're a Safari or Chrome user, for example.

Since this is a Firefox error code first and foremost, our solutions for it are also almost entirely Firefox-specific. Something to keep in mind moving forward with this article's content.

What does the SSL_ERROR_RX_RECORD_TOO_LONG error message mean?

Your ability to fix SSL_ERROR_RX_RECORD_TOO_LONG is likely to be nil, but understanding any given error code is rather important. In this case, the issue will usually relate to the implemented TLS version of the website you're accessing, and the error means that your device and/or browser cannot verify the absolute authenticity of the data you're viewing.

There's a number of things this might mean, of course. It may suggest that the website in question is subject to a misconfigured proxy. Alternatively, its selection of SSL certificates may well be fully out-of-date. Whatever the case may be, this error means that something is wrong server-side, and if you're not the server administrator, chances are good that you can't safely resolve the issue in any capacity.

What causes the SSL_ERROR_RX_RECORD_TOO_LONG error message?

Broadly speaking, there are usually two main reasons why a website might cause this error message to pop up.

  • The site's listening port may be incorrectly configured (it ought to use Port 443)

  • The site does not support TLS 1.2/1.3 (or the latest adequate TLS version)

As you can probably tell by now, these problems are specifically related to a website's connectivity configuration. A regular site visitor will not be able to alter its proxy settings nor switch over to the correct listening port, which means opening it up using HTTPS is all but entirely out of the picture.

Why am I getting the SSL_ERROR_RX_RECORD_TOO_LONG error?

You are getting this error because the proxy connection between your device and the website is unsafe and unverified, and it's impossible to vouch for the site's validity. As we've established above, it is a site misconfiguration problem in almost all cases, though there are some ways that users may be able to side-step the problem depending on how many risks they may feel like taking.

How to fix the SSL_ERROR_RX_RECORD_TOO_LONG error?

Albeit rare, it is sometimes possible to resolve this issue by completing a few key tasks in the Mozilla Firefox browser itself. Here's how to complete some of the safe options if you feel like giving them a shot:

  • Disable browser extensions
  • Reset the Firefox browser
    • Menu button -> Help -> More Troubleshooting Information -> Refresh Firefox... -> Refresh Firefox -> Finish (when done)

  • Clear cache in Firefox
    • CTRL + SHIFT + R or SHIFT + Reload button

  • Disable proxy in Firefox
    • Tools -> Options -> Advanced -> 'Network' tab -> Settings -> select the 'No Proxy' button

Should neither of these options fix the issue for you, there's one last thing you may be able to try: altering your security.tls.version.max preference setup. One important thing to understand about this fix is that it can open up your device to malicious activity, if you handle it incorrectly. This makes this method riskier than most, and you may wish to consider if accessing this website is worth the potential trouble. If it is, consider the next section.

How to change security.tls.version.max preference in Firefox?

For those who are dead-set on attempting anything and everything they can to access the troublesome website, this is effectively the last tweak we recommend doing. The caveat, however, is that you should absolutely not reduce your security level below a certain threshold. Let us explain.

For Microsoft Windows users, it may be possible to get improved site compatibility by dropping TLS support from TLS 1.3 over to TLS 1.2. We absolutely do not recommend dropping down to older versions of TLS, as they are legacy implementations that are easy pickings for malicious third parties.

To reduce your Firefox browser's TLS support down from TLS 1.3 to TLS 1.2, do the following:

  • Open a new Firefox tab and type 'about:config' into the address bar

  • Use the search field to filter the list to 'TLS' functionality

  • Find the 'security.tld.version.max' entry

  • Change the '4' to '3'

To reiterate once again: this method can be used to drop support to even lower-grade TLS implementations. Simply moving down from TLS 1.3 to TLS 1.2 is already a tad risky, however, and we cannot recommend attempting to "fix" your Firefox error by entirely disabling your online security. Disabling HTTPS would have a similar effect to doing so, and it is also highly inadvisable.

Will these fixes open up my device to malicious third parties?

The fixes outlined above won't open up your system to malicious third parties - if executed correctly. It is still not recommended to fiddle around with your operating system security if you absolutely don't need to. With that in mind, we firmly recommend sticking with the easier solutions mentioned earlier: try to reset Firefox and to tweak its proxy settings. You can even disable Firefox proxy entirely to see if that would work, though this is unlikely to have an effect.

Is SSL_ERROR_RX_RECORD_TOO_LONG a big security problem for you?

In almost every scenario, getting this error simply means that you cannot access the website. As already established, this is Mozilla warning Firefox users that the browser cannot vouch for the data's validity on the given website's IP address. This alone may be enough to put you off from accessing it. If not, sticking with the tweaks outlined above won't expose you to any serious security problems.

Again, however, it's worth reiterating that regular site visitors won't be able to fix this issue in most cases. Changing from (or back to) default settings or hitting the refresh Firefox button won't be of much help, and neither will accessing the site from an Incognito or private window. You are, however, free to try these options to see if anything gives.

Author: Paul Baka
Last Modified: 16/11/2022
Tags: #Articles