I'm running lighttpd/1.4.28 (ssl) on Debian Squeeze. I just created a http://startssl.com certificate, I runs fine at all of my Browsers (Firefox, Chrome, Opera), but my users are reporting certificate-errors in Firefox. I already nailed it down to a failing of loading of the certificate chain: Certificate at my Firefox: http://i.stack.imgur.com/moR5x.png Certificate at others Firefox: http://i.stack.imgur.com/ZVoIu.png (Note the missing StartCOM-certificates here) I followed this tutorial for embedding the certificate in my lighttpd: https://forum.startcom.org/viewtopic.php?t=719 The relevant parts of my lighttpd.conf look like this: $SERVER["socket"] == ":443" { ssl.engine = "enable" ssl.ca-file = "/etc/lighttpd/certs/ca-bundle.pem" ssl.pemfile = "/etc/lighttpd/certs/www.bisaboard.crt" } ca-bundle.pem was created like this: cat ca.pem sub.class1.server.ca.pem > ca-bundle.pem I grabbed the relevant files from here: http://www.startssl.com/certs/ www.bisaboard.crt was created like this: cat certificate.pem ssl.key > www.bisaboard.crt Where certificate.pem is my StartSSL-Class1 Certificate and ssl.key my SSL-Root-Key. Do you have any idea why the second Firefox does not correctly load the certificate-chain?