Cannot uplaod Monotouch project to device anymore - Null reference in installer

I have recently downloaded and inst开发者_JS百科alled Xcode 3 (!) together with SDK 4.3 (was on 4.2 before). Now i cannot deploy my app to iPad 2 (4.3.1) anymore. I get this error:

Please ensure your device is connected...
Connected to: René’s iPad
Initializing file service...
Uploading application
Finalizing file service...
Connected to: René’s iPad
Installing application

Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object
at MonoTouch.Installation.Installer.InstallApplication (object,System.EventArgs) <0x001b6>
at MonoTouch.Installation.Device.NotificationCallback (MonoTouch.Installation.Device/am_device_notification_callback_info&) <0x0006e>
at (wrapper native-to-managed) MonoTouch.Installation.Device.NotificationCallback (MonoTouch.Installation.Device/am_device_notification_callback_info&) <0x0003d>
at (wrapper managed-to-native) MonoTouch.CoreFoundation.CFRunLoop.CFRunLoopRun () <0x00003>
at MonoTouch.CoreFoundation.CFRunLoop.Run () <0x0000d>
at MonoTouch.Installation.Installer.InstallApplication (string) <0x00151>
at MTouch.Main (string[]) <0x032d1>

The application was terminated by a signal: SIGHUP

Your application name or path have a space in it. Remove the space and it should work.