OK, so I own 2 macs :

  • a MacBook Pro (running 10.8 with the latest Xcode on it)
  • an iMac (running 10.6 on one partition - Xcode installed and all - , and 10.7 - just installed - on another partition)

Note : all of Xcode versions + OSes have been purchased via the App Store

Now, here's my problem :

  • I'm signing in with my Apple ID
  • I'm going to My Purchases
  • Xcode is obviously there, BUT with the "Install" option, not the "Download" option
  • I'm clicking on "Install", it seems to be working for some time and then it either stops working or it throws an error message along these lines : "Something went wrong. Unknown error code."

I need your help guys. That's why I partitioned my iMac's drive in the first place : to be able to debug under 10.7 as well (see here: Install 2 different OS X versions on the same machine/hdd ).

So, any ideas???

Hint : I've also tried to find any instances of "Install Xcode" installers on my MacBook Pro, hoping that there would be some left (appropriate for 10.7 that is)... but unfortunately all I've found didn't seem to want to work under 10.7. So I'm stuck - I don't think there's any other way I could manage to re-install it, other than through the App Store, and the... App Store doesn't seem to be working... :S

3 Answers 3


Rather than install from the App Store, you could get Xcode from the download section of Apple's Developer Site. You may be required to create a developer account if you have one, but the free one should suffice, you don't need to sign up for the Mac or iOS developer programs.

This has the added feature of being able to choose precisely which version of Xcode you want, as it includes versions back to 2.2.1, from what I can see.


I have a similar setup, but I've got 10.6 on one partition, 10.7 on another and 10.8 on yet another partition. When the Mac App Store looks for installs, it will look at all the partitions for installed apps. I think that is your problem: it is already finding Xcode on your 10.6 partition.

Here is how I solved it and how I recommend you to do it as well:

Unmount your 10.6 partition after you boot into your 10.7 partition

If you want to do this automatically, you have to edit the file:


Inside of /etc/fstab, you need to place your partition's UDID like so:

UUID=68613ECB-3492-3B8B-9FFF-55FB1F30A32B       none    hfs     ro,noauto

noauto means don't automount it.

To find the UUID of your drive, launch Disk Utility, select the partition and then press the Info toolbar button. It will show you the UUID listed as Universal Unique Identifier.

Then reboot and you should find that your 10.6 partition is automatically not mounted.

At this point, the Mac App Store should look for Xcode, not be able to find it, and then allow you to install Xcode properly.


The reason that this happens is because the App Store detects any of the software installed on the machine, even if it wasn't through the App Store. To resolve this, and to be able to download/install XCode on your current partition, load Disk Utility and unmount the 10.6 partition. Then, load the App Store and install XCode. When it's done, remount the 10.6 partition in Disk Utility.

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