MacBook keeps booting into system installation after failed installation I did try to install Mavericks from the original installer package onto a separate disk via Firewire. The machine used is a MacBook Pro which is newer than the Mavericks package. As usual, after starting the installation from the desktop, the system rebooted to perform the installation after a minute or so. After rebooting it got stuck on a grey screen with a slashed circle on it. I did remember that Apple some when in the past introduced this nice feature to prevent installing an older MacOS on a newer Mac, so I booted into the recovery mode and installed on the external disk from there. So fine, so good - but when I unplugged the external disk to reboot into my normal system again, I ended up on the grey awful screen again - looks like the Mac insists to continue the failed installation which is not possible. Using the option key on booting to select my normal boot partition does not work, it does not show up. So I assume the installer has put something to mark this system as installing. I don't want to reinstall my entire system to get rid of it for several reasons. So now comes the question: What did it put there? I can handle a bash to clean it out manually, if I just knew what and where.

Thanks in advance,
  Peter
Use Internet Recovery to reinstall the correct build of Mavericks for your machine, your user account and applications will be unaffected.

When you've done that, re-download a fresh copy of the Mavericks installer from Apple. This will be the latest available build (10.9.5) and you should have no further problems if you install from that. I'd recommend you build a USB installer from the Mavericks installer so you don't have to worry about a hard disk failure, lack of internet connection etc. To do this you can use 3rd-party utilities or follow this procedure. Download the Mavericks installer but quit it when it tries to run. Take an 8GB USB stick and name it Untitled. Then run this command in Terminal...

sudo /Applications/"Install OS X Mavericks.app"/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/"Install OS X Mavericks.app" --nointeraction


As you noted, you cannot install an unmodified version of OS X on hardware newer than the OS X build, regardless of where it's being installed to.