If after updating to iOS 4.2 SDK you get a “Base SDK Missing” error:
- open Project settings and choose “Latest iOS” under Base SDK for All Configurations
- open your target and make sure the settings applies to it (in case you overrode it)
- (yes, somehow the “Base SDK Missing” error seems to stick)
- shutdown Xcode and reopen.
The SDK now is set.
- Login into the Provisioning Portal, click “Provisioning” on the left side column
- Renew your expired profile (or create new one) and download it
- Drag it over the Xcode dock icon (or add it into the Organizer)
- Remove old profiles from Xcode Organizer
- Open your Device target. Select the Build tab -> Code Signing Identity, and make sure the new profile is the one in use.
Xcode has the habit of not automatically updating its targets to use the newly installed provisioning profile. (Even if you physically removed the old one.)
At this point you should be able to rebuild the app.