Almost nobody will miss it but Goodbye my-hacks.php! • WordPress Help

It's already no less than 10 years that there is a file called my-hacks.php that served, and I say it was, to add customizations in WordPress . This file no longer works in WordPress.

Currently the king of customizations is the file functions.php of which we give good account in WordPress Help, so it is the one that should be the receiver , in your case, of your personalizations, of your hacks, which for that served my-hacks.php .