Google sites such as google.com should work fine.

Normally this error occurs on a website that is outdated in still supporting RC4 and one has a preference enabled.

RC4 support has been completely removed in Firefox 50 as it is no longer able to be overridden. https://www.fxsitecompat.com/en-CA/docs/2016/rc4-support-has-been-completely-removed/

https://blog.mozilla.org/security/2015/09/11/deprecating-the-rc4-cipher/

Separate Issue; Your System Details shows;

Installed Plug-ins

Shockwave Flash 23.0 r0 Shockwave Flash 20.0 r0
Having more than one version of a program may cause issues. You must remove the older programs. Then get the current full installer.

Flash: Grab the uninstaller from here: Uninstall Flash Player | Windows Uninstall Flash Player | Mac

Then reinstall the latest version.

Note: Windows users should download the active_x for Internet Explorer. and the plugin for Plugin-based browsers (like Firefox).

Note: Windows 8 and Windows 10 have built-in flash players and Adobe will cause a conflict. Install the plugin only. Not the active_x.

Flash Player Version: 23.0.0.207 Flash Player (Linux) Version 11.2. 202.643

https://get.adobe.com/flashplayer/ Direct link scans current system and browser Note: Other software is offered in the download.

https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, Win IE . . . .) Note: Other software is offered in the download.

FredMcD said

Flash Player (Linux) Version 11.2. 202.643 . . Note: Other software is offered in the download.

The current is 11.2. 202.644 as 11.2. 202.643 was the previous. http://www.adobe.com/software/flash/about/

The "other software" is only a issue for Windows users as Mac and Linux users do not get this on the flashplayer download page.

James said

The current is 11.2. 202.644 as 11.2. 202.643 was the previous.

Thank you. Without the distribution3 page its hard to look up.