Xcode won't open: "Mac OS X platform is missing"

Question

Xcode won't open. I had it running fine a couple of weeks ago. Now I get the following error message when Xcode tries to open:

Internal Error  
File:  /SourceCache/DevToolsBase/.../XCPlatformSpecification.m  
Line:  438  
Object:  <XCPlatformSpecification>  
Method:  loadAllPlatforms  
The Mac OS X platform is missing - cannot set a default platform.  

Any idea what caused this or how I can recover? Changes I have made to my system (Snow Leopard) in the last couple of weeks include (a) allowing Software Update to run and (b) installing Eclipse IDE. But the problem may or may not be related to these changes.

Answer 1

If /Developer/Platforms/MacOSX is missing, then there's really not much you can do with Xcode. Reinstall it from the Developer DVD or download.