Problem with my own redirects since upgrade

Hello,

I’ve upgraded my wordpress last night and I’ve come across a major problem. I have a seperate php file in the root directory called links.php. When I try accessing this in the url (https://www.mysite.com/links.php?redirect=https://www.msn.com) it just comes up with a 404 error and tries to find the variables in the url string?

Any ideas?

Thanks,
Ryan