Firefox Allow Self Signed Certificate

1 min read
Firefox Allow Self Signed Certificate

Firefox is no longer accepting my self signed SSL certificate on .dev domains, which I use for local development. I started seeing this error message: MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT. To get around this error, you usually can tell the browser add an exception to allow the certificate. But it appears the latest version of Firefox is not allowing the user to trust the certificate. 

Here are the steps to allow a self-signed certificate.

  1. Browse to about:config
  2. Search for “network.stricttransportsecurity.preloadlist”.
  3. Set it to false.

Now you should be able to add an exception for the self-signed certificate to Firefox.

Disclaimer: Disable the preloadlist could lead to security risk. I would recommend moving away from .dev when possible.