I am using a Macbook Pro (2018, 13 inch, 2.3ghz i5) from work, and the previous user had installed Xcode and a few other apps through their apple account. I have since deleted Xcode, but whenever I try to download Xcode again through the app store, or any app for that matter, I get the message "We could not complete your purchase - Unknown Error". I have signed out and in, restarted several times, and looked in the Error Console. The console gives the error "Purchase failed with error: " and I can't find more. error message Any help would be greatly appreciated so that I can finally get back to work!

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    "previous user"? You mean the machine hasn't been completely wiped clean since ownership was transferred? That's not good, you don't even own the OS until you do. See support.apple.com/HT201065
    – Tetsujin
    Commented Sep 4, 2019 at 15:46
  • The problem is that it is a laptop provided by the company, so on the computer there is an IT admin account, and a developer admin account. The developer admin account is what I was told to use. Commented Sep 4, 2019 at 15:54
  • I'd check with IT then, they may have it controlled by MDM.
    – Tetsujin
    Commented Sep 4, 2019 at 16:02

3 Answers 3


Quit your App Store application if it is open. Launch the terminal application and type the following command:

open $TMPDIR/../C/com.apple.appstore/

A folder named com.apple.appstore will open. Move all the files present in it to Trash. Restart your mac and launch the App Store again. Problem solved!


The reason for this is that:

Your Xcode application was installed previously with a different Apple ID. I would suggest you to check if there is any account active still in @Internet Accounts. Remove it and also go to Profiles and check if there is MDM profile installed or not. If you have an MDM profile, you have to reach out your IT to fix it.

Also, sign out from Mac Store and iTunes, reboot and try to sign in back if there is no MDM profile installed on your Macbook.

  • Signing out of App Store and rebooting fixed this for me Commented Nov 24, 2020 at 4:38

Removing contents of /var/folders and /private/var/folders cache directories fixed this issue for me. Open your terminal and run

sudo rm -fr /var/folders/**
sudo rm -fr /private/var/folders/**

Found this solution there

Do not be afraid to break something by removing contents from /var/folders and /private/var/folders because they are used to store per-user temporary files and caches


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