Failed to launch simulated application: Unknown error

Question

• OS X 10.5.7 (genuine Mac)
• Xcode 3.1.3
• iPhone SDK 3.0

When I try to execute my iPhone application in simulator, I get the dreaded error

Answer 1

I had a similar issue with a different solution: some of my .xib files had a deployment target (2.0) that was no longer installed on my machine.

The solution was to open the xibs in Interface Builder, do cmd-opt-I to get the project info for each one, and make sure the deployment and development targets were set to correct versions.

I then did cmd-shift-K to clean the project in XCode, rebuilt, deployed, and everything seems to work fine.