Craft CMS 3 admin panel returns 404 with SSL I'm using MAMP Pro for local development and was gong to set up my site with SSL this time around. I got a self-signed cert for local dev and I can go to my development site over https:// without any trouble but when I try to go to the control panel I get  404 error. I've updated the .htaccess file as suggested on Enforcing SSL for CP Requests but I still get a 404 error. All the Stack articles I could find on this issue were of no help either. Any suggestions? Something obvious that I'm overlooking?
tl;dr: In my case, adding AllowOverride All back in to httpd.conf fixed the issue.

I was having the same issue on my staging server. I noticed that, in addition to /admin throwing a 404, all of my site's subpages were 404-ing. This cause me to try the unrouted index.php url for a subpage (mysite.com/index.php?p=subpage) and it worked! Note, this wasn't working for /index.php?p=admin because it was properly routing to /admin/login. Plugging in /index.php?p=admin/login worked. 

I ran through the Craft guide for removing index.php from urls. Everything was set up properly, but my server admin found that AllowOverride All had been commented out of httpd.conf during a server update and was never un-commented. Adding AllowOverride All back in to httpd.conf fixed the issue.