Apple has made some important changes to Recovery mode which may affect all users of Macs which are running OS X or macOS and support the mode.

In most cases, you enter Recovery mode because of a problem with your Mac. There remain the two basic modes available:

• local Recovery mode, entered by holding down Command-R during startup. This tries to use the local Recovery partition on your startup disk to provide tools such as Disk Utility;
• remote or online Recovery mode, entered by holding down Command-Option-R during startup. This works over your Internet connection, and does not rely on tools on your local Recovery partition. It is normally much slower, but should work even when the tools in your local Recovery partition are damaged or unavailable.

These have not changed. However Recovery modes are also used as a means of reinstalling macOS / OS X when you cannot use the App Store, or want to remove all associations with your Apple ID. Depending on which Recovery mode you enter, reinstallation will use the currently installed version of macOS (in local Recovery mode), or a different version (in remote Recovery mode).

Apple has now changed the reinstalls available from these different recovery modes, and added another mode, as detailed here.

Therefore before performing any reinstall of macOS / OS X from a Recovery mode, you will need to work out carefully which of the Recovery modes you should do that from. If you can only enter a remote Recovery mode, then the choice is simple: if your Mac is running macOS 10.12.3 or earlier, then you can only enter the old remote Recovery mode, and the version of macOS installed will be that originally installed on your Mac (or the closest that Apple has to it).

If your Mac is running 10.12.4 or later, then you can choose between remote latest Recovery mode (Command-Option-R), which now installs the latest version of macOS compatible with your Mac (currently 10.12.5), or remote original Recovery mode (Command-Option-Shift-R), which will install the original version of macOS which shipped with your Mac (or the closest that Apple has to it). In most cases, the former will be preferable.

This becomes very complex when you can choose to start up in local or remote Recovery modes. To try to make that clearer, I have drawn up a flowchart (using Scapple) to explain the options, as shown here:

You can obtain this in full-res PDF format here: reinstall1

This is also complicated by the fact that some reinstalls of macOS / OS X will still be associated with your Apple ID. If you are reinstalling macOS in order to prepare your Mac for sale or disposal, then you must ask whether your Mac is still running OS X El Capitan or earlier. If you are, to remove that association with your Apple ID, you must start up in remote Recovery mode (Command-Option-R) and reinstall from that. Unfortunately that will take your system back to its original, and you will not then be able to update it without associating it with an Apple ID.

If you are running macOS Sierra and wish to remove any association with your Apple ID, you can use the new remote latest Recovery mode (Command-Option-R still!) to install the latest version of Sierra. However, there is a small gap here for Macs which are running Sierra 10.12 to 10.12.3 inclusive, as they cannot use that new mode (reinstall after Command-Option-R and they receive their original version of macOS), as that is only available in 10.12.4 and later.

Hasn’t this become a real mess?

If you spot any errors in the above, or in my flowchart, please don’t hesitate to correct me – this is now (needlessly) complex.