Equinox P2 IStatus returns code 10001 in Eclipse RAP application "Your original request has been modified. null children=[]"

Question

I have to work with an already existing Eclipse RAP application which contains of two features and around 40 dependencies.

Since the Eclipse RAP doesn't have a preStartup() method I call the update procedure in the RAP's start() method:

public class MyApplication implements IApplication
{
    @Override
    public Object start( IApplicationContext context ) throws Exception
    {
        P2Util.update(); 
        ...
    }
}

The IProvisioningAgent is not null, the IMetadataRepositoryManager and IArtifactRepositoryManager are correctly initialized.

public static boolean configureRepository( IProvisioningAgent agent )
{

   String repo = "file:///c:/export/repository/"; // TODO HERE!

   log.debug( "Initiliazing Repository Managers" );
   IMetadataRepositoryManager metadataManager = ( IMetadataRepositoryManager ) agent.getService( IMetadataRepositoryManager.SERVICE_NAME );
   IArtifactRepositoryManager artifactManager = ( IArtifactRepositoryManager ) agent.getService( IArtifactRepositoryManager.SERVICE_NAME );

   URI uri;
   try
   {
      uri = new URI( repo );
   }
   catch ( URISyntaxException e1 )
   {
     log.error( "Unexpected URISyntaxException, the specified path is not a valid URI", e1 ); //$NON-NLS-1$
      return false;
   }

   if ( metadataManager == null )
   {
     log.error( "IMetadataRepositoryManager instance is null!" );
     return false;
   }
   metadataManager.addRepository( uri );
   log.debug( "Added repository to MetadataManager: " + repo );
   if ( artifactManager == null )
   {
      log.error( "IArtifactRepositoryManager instance is null!" );
      return false;
   }
   artifactManager.addRepository( uri );
   log.debug( "Added repository to ArtifactManager: " + repo );
   return true;
}

Still one problem occurs all the time after I call checkForUpdates().

  public static IStatus checkForUpdates( IProvisioningAgent agent ) throws OperationCanceledException
  {
    log.info( "Checking for new updates in repository" );
    ProvisioningSession session = new ProvisioningSession( agent );
    UpdateOperation operation = new UpdateOperation( session );
    IStatus status = operation.resolveModal( new NullProgressMonitor() );
    return status;
  }

It returns the following status:

Status OK: org.eclipse.equinox.p2.operations code=10001 Your original request has been modified. null children=[]

I have already checked the flag "Support software installation in the launched application" in my run configuration, the problem persists.