Just recently I found myself using the $file->mime() function. While on my testserver there’s the newest php 7 version (as well as a switchable 5.6.) installed) I noticed with kirby 2.4.0 it’ll error out when using the mime() function, while on php 7 everything works without any error.
I’m obviously not quite sure if or where the problem is to be located, but generally it would be a great thing if the cheatsheet also shows X-Function has a requirement of >= PHP Version. Just when for example the new str::random() function “is working better” with php 7 acccording to what i remember on changelogs.