That’s odd. All it does it call File::startAsProcess()
on the DemoRunner.xcodeproj
file. Are you able to open that file manually?
I got a solution from Fabian at info@juce.com “If you are compiling the Projucer yourself, then you also first need to build the DemoRunner project in examples.”
I opened the example projucer for demo runner and build it in my IDE.