For the past two days, I’ve been receiving a security warning when logging into the DxO forum (using latest Firefox on Windows 11).
Please check / renew that certificate.
I wonder if it’s related to the Windows 11 secure boot certificate update. I don’t know much about it because I am still on Windows 10, and your problem may be totally unrelated, but I have seen several references to it online recently.
Mark
No probs on macOS here in France
Hi Mark,
so far it’s the only page showing this certificate problem.
greetings, Wolfgang
Same here, with last Firefox update on Win 11.
No issues with Chrome.
I would blame Firefox, in this case.
2 Likes
No problem here either - on latest Chrome
Yep - Looks that way.
No issue here with MS Edge on Win11 25H2 either.
Sounds like Firefox problem with trusted certificates.
See Connexion to DXO server impossible since 2025 08 01 - #18 by Wlodek for similar issue.
In my case, same as in SSLlabs, forum.dxo.com currently resolves to 5.196.172.220.
UPDATE: According to SSL Labs report, forum.dxo.com does not support TLS 1.3, but supports TLS 1.2, 1.1 (!), and 1.0 (!). This is an issue for DxO to look into.
On contrary, www.dxo.com, supports only TLS 1.3 and 1.2. Maybe you have disabled TLS 1.2 support?
I have no idea how to change / set this. 
I don’t know either, but maybe Firefox has some setting. AFAIK, on (latest) Windows 11, TLS 1.2 and 1.3 are enabled by default, while TLS 1.1 and 1.0 plus older, SSL versions, are disabled, for a good reason. But it still could be trusted root certificate problem, which looks more probable in your case.
I can only reach this forum via my phone as that’s still on FF v150. All my other devices are on FF v151 and they say that DxO are using a self signed certificate. Unsurprisingly, such a certificate is not trusted.
It’s only DxO sites that have become a problem. So I don’t see that this is a FF thing.
Until this is resolved I won’t be around. Bye for now.
SSL Labs test says otherwise – try SSL Server Test (Powered by Qualys SSL Labs) .
Only the root certificate from COMODO is of course self-signed, but that one should be in your trusted root certificates list (and in my case, it is).
Use Windows Settings → Network & internet → Advanced network settings → Internet options. New window ‘Internet Properties’ should appear, choose the ‘Advanced’ tab and scroll down. Win 11 pro 25H2 here.
Sorry, I’m lost.
I remember to have imported certificates in the past, but I don’t get it here.
I also have this problem with the lastest Firefox 151.0.1 (aarch64) on MacOS 15.7.7.