Super mysterious webpage bug

I made this program recently that emulates the signup/login process. I recently renamed login_process.php to process_login.php and signup_process.php to process_signup.php. I then upadated the formaction attributes of the submit inputs accordingly, and saved all the files. I go back later to test it, and when I click a button, I get 404 Not Found "The requested URL / ... was not found on this server" error. This error uses the OLD name of the target page, and when I close that and open the preview again to the starter form page, right click, and click "View page source", the formaction attributes of the submit inputs are shown to have the value of the old name of the target page as well, even though they are correct in workspaces! I downloaded the workspace hoping to put it here, but there doesn't seem to be a way to do that (someone let me know if I'm wrong). I'll try to see if I can upload it to GitHub or MediaFire and get the shareable link to put here asap. EDIT: Here is the MediaFire link