How to disable «Secure Connection Failed» for all visited sites?

Question

UPD: Problem was reproduced for me in Windows 10 EN Enterprise LTSB 64-bit. I install Windows → I download browsers (more I do not download anything after installation) → I get same errors.

---

1. Problem

For example, I visited https://bower.io/ site. Instead of site content I see Secure Connection Failed:

When I visited a lot of sites, I see Secure Connection Failed. How I can disable it always, for all visited sites?

I detect these problem about half-year — almost at the same time as I bought a mew computer. The vast majority of sites open normally for me, but for some sites I get Secure Connection Failed.

I don't think, that bower.io or another sites banned in Russia — my country.

---

2. Environment

1. Windows 10 x32,
2. Firefox 50.0.1,
3. I'm not use antiviruses or others anti-malware applications,
4. I'm disable Windows Firewall and others Windows security tools.
5. I'm not use proxy.

---

3. Not helped

1. The problem reproduced for me in Firefox Safe Mode.
2. I check my computer on viruses, use HerdProtect. I have not malware in my computer.
3. I can not visited https://bower.io/ via Internet Explorer 11.576.14393.0 and Chrome 55.0.2883.87 m:

4. I change values for security.ssl3.dhe_rsa_aes_128_sha and security.ssl3.dhe_rsa_aes_256_sha in Firefox configuration.
5. I delete cert8.db file into my profile, but if I run Firefox again, cert8.db was created for me again.
6. I add .eg top-level domain, to bower.io, but that site still not open for me.
7. I update internet time:

---

4. Do not offer

1. Please, don't tell me, that my computer is more vulnerably, I reduce my security and so on. I understand it, but I do not matter want to disable Secure Connection Failed.
2. Please, do not offer solutions, how I can set my sites, that no get Secure Connection Failed. I'm not owner of the sites, which I visited.
3. Please, do not offer solutions, how to disable for each site separately. I don't want wasting my time to add an exception for each site, I want solution for all sites at once.
4. Please, do not offer to use Browsec VPN or other VPN addons. I use Browsec VPN in my Firefox, and that visited https://bower.io/, I need enable Browsec VPN → visited bower.io → disable Browsec VPN, because, it works slowly. I want to visited bower.io in «normal mode», without proxy or VPN.

Answer 1

The Reasons can be many. I would like to suggest few

• Check that you are under proxy by navigating to about:preferences#advanced, Open Connection Settings. Example settings preview: Image
• Check the application that you're running. If you are running from a shortcut then the shortcut could be edited and running a malware app then that app is running firefox with some modified settings. Try running firefox from the {original installed location}/firefox.exe
• If the shortcut's target url contains different path or contains any arguments to firefox then there's a malware installed in your browser. Check the installed addons/extensions. Uninstall untrusted addons.

Hope this solves your query.