title: Self-signed *.dev cert untrusted using Firefox 59 on Ubuntu
body: <p>I am using Firefox 59.0.1 on Ubuntu and I am seeing the following error when accessing my development environment which is behind a self-signed SSL cert.</p>
  
  <blockquote>
    <p>Your connection is not secure</p>
    
    <p>The owner of crmpicco.dev has configured their website improperly. To
    protect your information from being stolen, Firefox has not connected
    to this website.</p>
    
    <p>This site uses HTTP Strict Transport Security (HSTS) to specify that
    Firefox may only connect to it securely. As a result, it is not
    possible to add an exception for this certificate.</p>
    
    <p>Learn more…</p>
    
    <p>Report errors like this to help Mozilla identify and block malicious
    sites</p>
    
    <p>crmpicco.dev uses an invalid security certificate.</p>
    
    <p>The certificate is not trusted because it is self-signed.</p>
    
    <p>Error code: SEC_ERROR_UNKNOWN_ISSUER</p>
  </blockquote>
  
  <p>I have added "crmpicco.dev" to security.tls.insecure_fallback_hosts and set security.enterprise_roots.enabled to true, restarted Firefox but this has had no effect.</p>
  
  <p>I know Chrome has their "badidea"/"thisisnotsafe" workaround, which I know isn't ideal but it at least works - whereas I am yet to find a Firefox equivalent.</p>
  
  <p>What is the solution for this? Do I need to generate new self-signed certs even although the cert I have is from Feb 2018.</p>
  
  <p>I have tried the numerous questions on here and Mozilla support to no effect.</p>