The site specified an invalid Strict-Transport-Security header - firebug
I am getting this warning in firebug when adding HSTS header. The site specified an invalid Strict-Transport-Security header. here is my htaccess <IfModule mod_headers.c> Header append X-FRAME-OPTIONS: SAMEORIGIN Header append Strict-Transport-Security: 'max-age=31536000; includeSubDomains' </IfModule> When I remove quotes from the value I get Internal Server Error . Website is being served through https, redirect from http to https is set from apache's site file. SSL certificate is self-signed, if it matters. mod headers is enabled. Im on debian 7, apache 2.2. Thanks As @jhutar mentioned in