Just tried switching to Gitlab Next and ran into a bad SSL certificate error message. The cert being served seems to be only valid for *.gitlab.io and gitlab.io
Here is the full error message from Firefox -
Websites prove their identity via certificates. Firefox does not trust this site because it uses a certificate that is not valid for next.gitlab.com. The certificate is only valid for the following names: *.gitlab.io, gitlab.io
Works fine for me in Firefox I don’t get any such error. Maybe you have a previous certificate in your Firefox cache causing the problem. Suggest going into Firefox history, search for next.gitlab.com then right click on it and forget this site. Close Firefox and try again.