Qt error: one or more PCH files were found, but they were invalid

> Hi, I was experimenting with the cocoa echo server example and last nite I tried to build it and got the folowing errors
> for compiling main.m
> 
> cc1obj: error: /var/folders/QM/QMo9W4UfHbyT7aaah168pU+++TI/-Caches-/com.apple.Xcode.501/SharedPrecompiledHeaders/CocoaEchoClient_Prefix-bgczgeitlorctgffmkvyzeuaskzg/CocoaEchoClient_Prefix.pch: No such file or directory
> 
> 
> cc1obj: error: one or more PCH files were found, but they were invalid
> 
> cc1obj: error: use -Winvalid-pch for more information
> 
> 

This append after an update of the compiler. Just clean your project (cmd + K) and retry.

-- Jean-Daniel