RapidWeaver Error Warning - Multiple Index Files

This warning is telling you that you have two index files. This usually happens because you built the page in default html mode, your home page is then saved as index.html. And then if you add something (an Element or a Stack) that needs a .php extension, it will create an index.php file.

Since RapidWeaver does not remove any files from your server you end up with two index files. You can check in your cPanel File Manager or by using an ftp app,

Chances are, you need to delete the index.html version. Always best to look which is the most recent (updated) file by looking at the date modified/created.