ios simulator - iPhone: Failed to launch simulated application: Unknown error

Question

This is a new iPhone project, only 1 target (different from this question)

On build we get:

Failed to launch simulated application: Unknown error.

The google again gives us nothing, lots of people have encountered this and there are lots of crazy ideas to try "oh clean the build", "clear the cache", "twiddle this flag" and none of them work and work consistently. We can reproduce this on two different machines with SDK 2.2.1 and 3.0 beta. Not the install on the machines since other iphone projects work just fine so we believe it has something to do with the config of this particular project but after combing through the config twice we can't spot the problem.

Vanna, I'd like to buy a clue for $200 please.

• Tried: XCode menu->Clear cache
• Tried: clean all targets
• Tried: rm -rf ~/Library/Application Support/iPhone Simulator

Answer 1

This happened to me once and I think I saw in a blog to simply quit and restart Xcode. Miraculously, it worked for me. I doubt this is the end all solutions to all problems like these though, but if you haven't yet closed Xcode, it's worth a try.