Ad hoc builds (Xcode 4.2, Lion) won't install on 4.2.1 devices

With Lion around the corner I recently installed the GM and tried to build some 开发者_高级运维of my projects using Xcode 4.2, which includes the iOS 5 beta 2 SDK.

Ad hoc builds installed just fine on several iPhone 4s running iOS 4.2, 4.3 and 5.0. The installation failed on 2 3GS devices running 4.2.1. Is this due to the devices or the OS versions?

To clarify: There is no Xcode 4.0 or 4.1 for Lion (as of now), so I'll be "stuck" with 4.2 once Lion hits the App Store. 4.2 includes the 5.0 SDK which may be the cause of this issue.

Any hints?

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XCode 4.2 is not going to be released with Lion - 4.1 will. It is available to Mac developers and WWDC attendees at this time, but should be released for everyone when Lion is. Apple will not support using XCode 4.2 to submit apps to the store, and it currently does not support previous versions of the SDK as all their efforts are on new features for iOS 5.