App Store on OS X broken after system restoration from backup I recently had to restore my installation of OS X 10.9.4 from a backup. Since then(*), the App Store application is broken. It displays an empty window showing the MAS symbol and the menu bar. Clicking icons in the menu bar highlights them all. Nothing else happens. See the console output below:


  01.10.14 19:09:08,079 storeagent[759]: * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* setObjectForKey: key cannot be nil'
  *** First throw call stack:
  (
      0   CoreFoundation                      0x00007fff8c63425c __exceptionPreprocess + 172
      1   libobjc.A.dylib                     0x00007fff8cdb1e75 objc_exception_throw + 43
      2   CoreFoundation                      0x00007fff8c52f22e -[__NSDictionaryM setObject:forKey:] + 1102
      3   storeagent                          0x000000010e751b0b storeagent + 31499
      4   libdispatch.dylib                   0x00007fff904df1bb _dispatch_call_block_and_release + 12
      5   libdispatch.dylib                   0x00007fff904dc28d _dispatch_client_callout + 8
      6   libdispatch.dylib                   0x00007fff904de673 _dispatch_queue_drain + 451
      7   libdispatch.dylib                   0x00007fff904df9c1 _dispatch_queue_invoke + 110
      8   libdispatch.dylib                   0x00007fff904ddf87 _dispatch_root_queue_drain + 75
      9   libdispatch.dylib                   0x00007fff904df177 _dispatch_worker_thread2 + 40
      10  libsystem_pthread.dylib             0x00007fff96e9bef8 _pthread_wqthread + 314
      11  libsystem_pthread.dylib             0x00007fff96e9efb9 start_wqthread + 13
  )
  01.10.14 19:09:08,519 com.apple.launchd.peruser.502[163]: (com.apple.storeagent[759]) Job appears to have crashed: Abort trap: 6


Enabling the debug menu (terminal: defaults write com.apple.appstore ShowDebugMenu -bool true) and resetting the application had not effect (same console output as mentioned above). 

I installed OS X 10.9.5 using the terminal. The Mac App Store application worked until the next reboot. 

What can I do short of reinstalling OS X from the recovery partition?
There are several Options you could try in order to identify the source of your troubles:


create a new User and try to access the AppStore with your current ID (or a temporary one). If it works, the Problem lies within your User-Profile and not the OS. If it doesn't, the Problem is located in the OS (or the Drive itself).
OS &amp; User-Profile: try clearing out the Cache files, either manually (see f.e. StackExchange Article here) or use the freeware 'Onyx' (my preferred method)
OS: Check the Harddrive and the File System Permissions with Disk Utilities.app (found in /Applications/Utilities). It is possible (but not liklely) that your HD or Filesystem is defective/corrupt.
User-Profile: go to ~/Library/Containers/ an move the Folder com.apple.appstore somewhere else, f.e. the Desktop. Try starting the App Store again. 


Try these and if it doesn't work look in the console. perheaps there are news error messages there.