Hello...

Type about:preferences#advanced<Enter> in the address bar.

Under Advanced, Select Network. [56+] Type about:preferences#general<enter> in the address bar. Look for 'Network.' +++++++++++++++++++++ Look for Configure How Firefox Connects and press the Settings button. If you are using a proxy, make sure those settings are correct. If there is no proxy, first try No Proxy. If there is a problem, then try System Proxy.

Some problems occur when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

   * Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
   * Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see
  
  Configure firewalls so that Firefox can access the Internet  

thank you..

https://www.bing.com/search?q=pr_end_of_file_error

radi.stoyanov said Turns out the option DNS over HTTPS is what caused the problem.

jamesafuf123 said https://support.mozilla.org/en-US/questions/1264659#answer-1237475 my ISP was blocking sites like that

cor-el said This usually means that Firefox wasn't able to find a cipher suites to use to connect to this server and reached the end of the list. There can be two possibilities: one is that the server is outdated and doesn't support modern cipher suites, another might be that the server only supports a few cipher suites and Firefox doesn't support any of these.

You can check your browser and possibly compare this with the server setup.

• https://www.ssllabs.com/ssltest/viewMyClient.html