@RichM I was having the same issue but was able to work around it. The error I was getting was You attempted to reach ..., but the server presented an invalid certificate. NET::ERR_CERT_INVALID I was able to visit the page in Firefox and "proceed anyways" on the error screen which added a security exception to Firefox. Then I was able to download the self signed cert in Firefox (click on lock icon in address bar > click on ">" to the right of "Connection not secure" > More Information > View Certificate > scroll down to Download section and click "PEM (cert)" to download it), add it to my keychain (Keychain Access app > System > Certificates > click the "+" icon and choose the cert you downloaded above), edit it in the keychain (right click the newly added cert in the Keychain app > Get Info) and mark it as "Always Trust" (expand Trust section > "When using this certificate" > "Always Trust"). After that I quit and reopened the browser and was able to expand the Advanced section of the error page and "Proceed to ... (unsafe).".