Q&A: Permissions not repairable

Q All of a sudden, when I try to move files onto my internal hard disk, I am shown a dialog stating that I do not have permissions to do that, and prompting me to authenticate. Once I have done that, it works fine. Disk Utility will of course no longer repair permissions. What can I try instead?

A This is a permissions problem. To establish its cause, you need to know whether you are logged in as an admin user, and the permission settings for the folder into which you are trying to move the items.

If this is the top level of your hard disk, then you should no longer do so, but choose a more appropriate folder such as one in your Home Folder, or /Users/Shared. This is because the top or root level of your startup volume is protected for better security, and keeps it clear and clean from the clutter of working files.

If you really must put them at that top level, select the disk in the Finder, press Command-I to show the Get Info dialog, and ensure that the owner is system with read-write permissions, the group is wheel with only read permissions, and the bottom line gives everyone read-only access too: this will require authentication each time, which is the new standard, I am afraid. Use the same technique to check permissions on other folders.

If you are are trying to move these files into your Home Folder, or a folder within that, then the permissions set for that should allow that without any further authentication. Again, use the Finder’s Get Info dialog to correct them if necessary.

If the permissions appear correct, there are two possibilities. Those permissions could be ‘wobbly’, because of a minor disk error which you can repair using Disk Utility in Recovery mode (Command-R at startup). Otherwise an app or extension is fiddling with permissions, something which should be apparent in your logs.

If you cannot identify the culprit from the logs, try restarting with the Shift key held down to block third-party extensions. If the problem goes away you next need to identify which extension it could be.

Comments The reason that Disk Utility in El Capitan no longers offers the ability to repair permissions is related to the extended security protection of SIP. This now prevents access to, or tampering with, most of the key system folders.

A user-run process, such as repair permissions in Disk Utility, would no longer be able to check or repair the most critical permissions settings. So OS X only performs such repairs as part of updates to the system, when SIP permits. This means that you now have the responsibility for keeping your own permissions – particularly those in your Home Folder – in order.

Updated from the original, which was first published in MacUser volume 28 issue 12, 2012.