System Integrity Protection, also known as "rootless," is a technology introduced by Apple that prevents any application from reading or writing to files within the "System" directory on your Mac. Some of our applications are affected by this, and in order to get them to work in OS X El Capitan (10.11) or later, you will need to disable it. Disabling SIP is relatively easy to do. See our support article about SIP for more information and instructions.
As System Integrity Protection is a security measure, you may be wary of anyone asking you to disable it. Below you can find a list of which applications of ours are affected, and the reason why.
XRevert
There are too many files to list, but the only files that XRevert needs to add to the System folder are icon files, to replace some of the macOS icons which reside there.
For the aesthetic changes that XRevert makes, it needs to replace a file called "SystemAppearance.car," which manages these aesthetic elements.
Ringtone Adder
Ringtones are stored in a subfolder of the file "ToneLibrary.framework." Ringtone Adder will ask you to select an .m4r file (or multiple .m4r files), and the only files that get added to that folder are the ones that you specify.
Ringtone Adder needs to make changes to a file called "TKRingtones.plist." It needs to add the names of the ringtones you've added to this file in order to get macOS to recognize them.
Read our support article for instructions on disabling SIP: