If you are experiencing strange crashes while refreshing provisioning profiles and if console output looks like this:

4/1/13 11:33:34.990 PM Xcode[16011]: DVTAssertions: UNCAUGHT EXCEPTION (NSInvalidArgumentException): *** setObjectForKey: object cannot be nil (key: teamId)
UserInfo: (null)
Hints: None

don’t worry there’s a quick fix. Just remove (or move somewhere else, or rename) this file:

~/Library/Developer/Xcode/connect1.apple.com 4.6.1.db

This fix worked for Xcode 4.6.1  and It might also apply other versions.

Source:

http://stackoverflow.com/questions/15434296/xcode-crash-when-refreshing-provisioning-profiles