Apple Configurator V1.4 was working this morning, now quits immediately upon start
Delete the Apple Configurator preference file and try running the app again.

rm ~/Library/Preferences/com.apple.configurator.plist

Delete the Apple Configurator file containers and try running the app again.

sudo find /private/var/folders -name com.apple.configurator -delete





These files should not contain any important information regarding your devices and/or settings in Apple Configurator. Both the preferences .plist and the containers didn't contain anything important, and after making a backup I ran the above commands on my machine - it didn't cause any problems. All my settings remained in the app.

However, this doesn't necessarily mean it will be the same for you. You can check the contents of the containers by running the following command (I've also included my output so you can compare if you wish):

sudo find /private/var/folders -name com.apple.configurator | xargs tree
/private/var/folders/hh/41_x4gjd5sl_fmdsmglz94xw0000gn/C/com.apple.configurator
├── com.apple.scriptmanager.le.cache
└── mds
    ├── mds.lock
    ├── mdsDirectory.db
    └── mdsObject.db
/private/var/folders/hh/41_x4gjd5sl_fmdsmglz94xw0000gn/T/com.apple.configurator
└── TemporaryItems
    └── (A\ Document\ Being\ Saved\ By\ Apple\ Configurator)
3 directories, 4 files




As per this Apple KB article, the Apple Configurator's actual data is stored in ~/Library/Containers/com.apple.configurator. If, once you have followed the instructions above, the app still does not work, backup this folder and delete it. If the app works after you do this, and you need your data back, restore this folder from your most recent backup.