Mozilla browser SSL issue


I think your SSL Certificates are not working on Firefox anymore. I dont know why but on Chrome, MS Edge, IE working well.

Thank you for your help.


Hi @sero

looks like your Firefox is broken.

Own Firefox screenshot:


The certificate is green and valide.


What is your Firefox-Version?
I have 64.0 (64-bit) and I think latest Version has new Security-Patch.


You aren’t sending the intermediate certificate from That’s the most likely cause for your failure.

If you were able to visit this forum without errors, then there’s nothing wrong with Let’s Encrypt and your browser.


My Firefox is the same - 64 + 64 bit.

Ssllabs shows an incomplete chain:

Certificates provided 1 (1393 bytes)
Chain issues Incomplete

The server sends only one certificate, not the intermediate certificate.

But this is a problem of this server configuration.

And browsers often ignores that error.


The -dev system seems to have gotten the cert chain done correctly.
But login & -stg, don’t have intermediate cert.

www also has problem with IPv4 access (IPv6 works well):

[maybe unrelated - maybe it is] underlying system:
does serve the full cert chain

And: none of the systems on that IP appear to have server cipher preference ordering on.


Certbot installed on my server but it served only cert.pem, which must be fullchain.pem.
Thank you all for your help


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