Recently, I began work on an iPhone app and during testing I came across this error:

“The version of iPhone OS on “Gustavo Tandeciarz’s iPhone” does not match any of the versions of iPhone OS supported for development with this copy of Xcode…”

I have the latest version (3.0.1) on my iPhone, which is apparently not supported, yet by Xcode so until then, I need a work around.

Searching Google, I found this little gem:

Open Terminal and run the following:

ln -s /Developer/Platforms/iPhoneOS.platform/DeviceSupport/3.0\ \(7A341\)
/Developer/Platforms/iPhoneOS.platform/DeviceSupport/3.0.1

Restart Xcode and try again. This worked perfectly on both of my Macs.