I have just upgraded my local machine to OSX Yosemite which has changed my Apache version from 2.2 to 2.4 and my PHP version from 5.4 to 5.5.
When I visit both example.dev/user and example.dev/user/login and enter my username and password, the login form appears to post the data and then 'loops' back to it's original state i.e. blank fields.
This is the same across all websites and all browsers and is the same for all users.
There is nothing in any of the error logs but…
"POST /user HTTP/1.1" 404 16744
… in the access logs
Has anyone encountered a similar problem?