Self-signed trusted root certificate is not recognized by Edge


For development, my team is using a self-signed SSL certificate. After installing the certificate in my machine's Trusted Root Certification Authorities store, the SSL certificate is recognized as valid in Chrome and IE 11:

Internet Explorer 11:

Internet Explorer 11

Chrome 69:


But Edge (version 42) seems to be ignoring the certificate:


Based on the message I'm getting from Edge ("This might be because the site uses outdated or unsafe TLS security settings"), I thought that my local development server might be using an outdated TLS version, but I can verify in Chrome's development tools that traffic is being encrypted using TLS 1.2:

Proof that I'm using TLS 1.2

Why does Edge seem to be ignoring my self-signed certificate that I have installed as a Trusted Root Certificate? How can I fix it?

Things I've tried:

  • Installing the same certificate in my Personal and Intermediate Root Certification Authorities stores
  • Restarting my machine

Best Solution

After quite a bit of investigation, we discovered the root cause - our company's antivirus software (Sophos) is blocking Edge (and only Edge) from reaching internal IP addresses. Edge's error message - "outdated or unsafe TLS security settings" - was misleading; Edge's requests weren't able to make it to the wire at all.