Firefox redirects to https

Question

"Sites preferences" are the culprit. Wasted 45min of my life finding how to fix it despite all the kb/support.mozilla tricks which does not solve your issue nor did mine. I don't know what triggers this issue, but several of my websites started to go pear-shaped in a few weeks only affecting me and only firefox.

That's the solution you are all looking for:

1. Go to Preferences
2. Privacy
3. Click 'Clear your history' (nothing will happen yet, click safely)
4. Once the pop-up appears, click Details.
5. Untick everything except 'Sites Preferences'
6. Select 'Everything' in the select box at the top
7. Click Ok
8. Try now

PS: What I did try that did not worked for me are:

• urlbar.autofill false
• Forget Website trick
• Safe mode
• We all know it is not an HSTS issue when a website you own and you accessed before never got https support but now FF wants you to use https... It is just a firefox bug IMO.

The solution that worked for me:

1. Go to about:config
2. Look for network.stricttransportsecurity.preloadlist and set it to "false"
3. Enjoy

If the above STILL DOES NOT WORK, try setting browser.fixup.fallback-to-https to "False" from about:config

I had the same problem but the answer was that I used a .dev extension to access my local websites !

I cleared all historic data in FF and nothing changed.

Searching for another solution, I found this page https://ma.ttias.be/chrome-force-dev-domains-https-via-preloaded-hsts/

With .dev being an official gTLD, we're most likely better of changing our preferred local development suffix from .dev to something else. If you're looking for a quick "search and replace" alternative for existing setups, consider the .test gTLD, which is a reserved name by IETF for testing (or development) purposes.

I changed my local website extensions from .dev to .test and all work perfectly !

Check your extensions!

In my case, DuckDuckGo Privacy Essentials extension was causing this redirect. I disabled it, and the problem is solved.

None of the answers worked for me, the only the one was the one in the comment of Muhammad so thanks in advance to him, I copy the answer here to make it easier:

• Go to about:config
• Look for browser.fixup.fallback-to-https and set it to false