Hi Jess,
Is this a new installation (i.e. you have no prior created sites to preserve)? It sounds like your installation might be incomplete and/or missing a critical file. Can you furnish us with a screenshot of what you do see when visiting http://localhost ?

This problem might happen if you had XAMPP installed prior and/or are running the installer’s “Upgrade” option in lieu of a new installation. If you have not already done so, please perform a manual installation (which is very easy), here is how:

1) Restart your Mac (via “Apple” menu upper left). If prompted, uncheck “Reopen windows when logging back in”
2) After login, simply drag the XAMPP folder from the zip archive’s lib folder to your Application folder:


Please let us know if this does not resolve the issue or if you need further assistance.