Firefox doesn’t trust SSL/HTTPS certificate

Although Chrome and Safari do open my site, Firefox does not trust the HTTPS/SSL certificate, anyone have an idea what is going wrong ?

Can you post a screenshot? But you’ll most likely have a broken certificate on your server and an insecure encryption mode on Cloudflare. If that is the case you need to fix both.

Hi sandro,

Certificate on server I renewed twice, the SSL/TLS encryption mode at Cloudflare is Full (strict)

Here is a screenshot … in Dutch however.

Can you switch your browser to English. I can’t really tell what the error is.

Assuming your server IP address ends in 92, you’d have a valid certificate on your server, as well as a valid certificate on the proxies, so the connection should be actually fine.

For me it loads fine on Firefox, so I’d assume this is a local issue. Restart your browser and clear the cache as well.

I restarted, and cleared the cache, problem is the same. I also get messages from other visitors using Firefox

Loads fine for me

Maybe try a fresh browser profile.

What’s the output of these commands?


I’m using 90.0.2 (64-bit). Visitor contacting me I’m not sure …

You removed the exact part that was important.

Again, post the exact output of those four commands.

This is two commands. What about the other two?

All right, you are resolving the right addresses, so it shouldn’t be a DNS issue.

Considering that you seem to be on a Unix system I’d try this command next

curl -Iv

What does it show?

You removed half of the output once more, but I assume that worked. So I am afraid that will be an issue with your Firefox setup. The connection itself is working.

Make sure you don’t have a proxy or something setup in Firefox

What version of firefox are you using if i may ask?

As I wrote, I’m not the only one with this problem, two other visitors (with a Firefox browser) to my site reported the same thing. One of them is a Windows user…

I understand, but the site is loading for me, it loads at, and it even loads on your command line.

That is not a Cloudflare issue nor even a connection issue but will be something about your Firefox profile (and possibly your users’) but that’s something you’d need to clarify on a Firefox forum. If you use the same ISP, for example, and have the same proxy you might run into the same issue, but that’s still a local issue I am afraid.

The site itself is working fine.

As I mentioned earlier.

After they reported this to me, I (Safari user) downloaded Firefox today and noticed the same problem. So I had a fresh version of Firefox…

I will present this problem on a Firefox forum then…

Anyway, thanks for your help Sandero, much appreciated !!!