Cert served by FritzBox won´t work in FireFox 47


I’ve just got certificates and imported those on my FritzBox router. Serving the fritzbox admin ui over SSL works fine on Safari and Chrome but Firefox 47 complains: SEC_ERROR_UNKNOWN_ISSUER

Firefox claims (translated): the certificate is not verified since the issues is unknown.

What I’ve uploaded to the fritzbox is the concatenated cert.pem and privkey.com

DNS name available per pm.

Note: Firefox does not show a hierarchy of this certificate. Maybe the concatenation should include others files, too, before uploading to the fritzbox?



You need to also serve the intermediate certificate, which you can find in chain.pem or fullchain.pem. How to configure that depends a bit on what web server is being used, but there is an additional object that needs to be a part of the configuration beyond cert.pem and privkey.pem.


You’re not serving the intermediate cert. Use fullchain.pem instead of cert.pem or concatenate cert.pem, chain.pem and privkey.pem which has the same result.


Thank you both. Had read about an additional certificate option for Apache but wasn’t sure how to handle this for the FritzBox.

Summary: for using letsencrypt with the FritzBox you need to concat the fullcert and private key and upload the resulting file:

cat fullcert.pem privkey.pem > fritzbox.pem


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