Last week I updated to High Sierra and now can no longer log into the EE admin interface on localhost.
Since High Sierra installs PHP 7, I added PHP 5.6 as my default, but no change. I enabled debugging in both index.php and my admin php, but no errors are shown. No errors in the Apache log either, the admin pages are served with a 200 return code.
The mystery bit is that the site itself is working (albeit very slow).
When running the EE Server Compatibility Wizard it works on and off, and if it does it reports my system to be compatible for an EE install.
I've run out of things to check. Do you have any advice?
Edit: It seems to be an issue with a timeout with calls of the PHP function 'set_time_limit'. If I comment them out (in Codeigniter.php line 108, Core.php line 64), the admin login works.