If you are trying to connect to a website over a secure connection over the HTTPS protocol, then it requires the use of SSL certificates by those websites. These certificates are used to encrypt and later decrypt all the data sent or received from the web servers where these websites are hosted. But when something happens to the secure data anywhere in the long chain of computers and networks connecting your PC to the web server, then a web browser like Mozilla Firefox cannot verify the secure data and shows an error.

One of these errors displayed by Mozilla Firefox is SSL_ERROR_RX_RECORD_TOO_LONG. This error is usually displayed when the SSL certificate on the web server is not properly configured.

Firefox SSL Error

Here is what you can do to fix this error:

  1. Try connecting to the website over HTTP: If there is some problem with the SSL certificate on the web server, perhaps you can skip the HTTPS secure protocol altogether and connect to the website over the insecure HTTP protocol. You can do this simply by removing https:// from the website URL and adding http:// in its place.
  2. Disable Firefox add-ons: Some of the Firefox add-ons could also interfere in the way Firefox sends requests to web servers. For example, some add-ons might be hard-coded to connect to web servers over the secure HTTPS protocol and this could easily cause error in case of a missing SSL certificate or a mis-configured certificate. You can access all the installed add-ons by entering about:addons in the address bar.
  3. Refresh Firefox: If the error is being caused due to some settings related mess that you’ve caused yourself, then you can still fix the problem by refreshing all the Firefox entries. To do this, you have to enter about:support in the address bar and then click on the Refresh Firefox button to remove all the customizations and settings.

If even after trying the previous steps, you seem to keep getting error then perhaps your ISP is tempering with the data being sent or received by your computer. In this case, you should try using a VPN proxy software like Hotspot Shield, Tunnelbear or CyberGhost.