LArSoft

Marco reported an issue with running backtracker on MicroBooNE corsika MC.
setup uboonecode v06_34_00 -q e14:prof

lar -c standard_ana_uboone.fcl /pnfs/uboone/mc/uboone/reconstructed/prodcosmics_corsika_cmc_uboone_intime_reco/reco/prod_intime_fix_v06_26_01/prodcosmics_corsika_cmc_uboone_intime_0_20170410T222014_gen2_13def821-c925-4deb-b6db-1eedbf20cb3e_20170419T053704_reco1_20170419T061659_reco2.root

%MSG-s ArtException:  PostProcessPath end_path 02-May-2017 20:01:06 CDT  PostProcessEvent
cet::exception caught in art
---- EventProcessorFailure BEGIN
  An exception occurred during current event processing
  ---- EventProcessorFailure BEGIN
    An exception occurred during current event processing
    ---- ScheduleExecutionFailure BEGIN
      ProcessingStopped.

      ---- ProductNotFound BEGIN
        A request to resolve an art::Ptr to a product containing items of type: simb::MCTruth with ProductID 1:9
        cannot be satisfied because the product cannot be found.
        The productGetter was not set -- are you trying to dereference a Ptr during mixing?
        cet::exception going through module
      ---- ProductNotFound END
      Exception going through path end_path
    ---- ScheduleExecutionFailure END
  ---- EventProcessorFailure END
---- EventProcessorFailure END
%MSG
%MSG-s ArtException:  PostProcessPath end_path 02-May-2017 20:01:06 CDT  PostProcessEvent
cet::exception caught in art
---- EventProcessorFailure BEGIN
  An exception occurred during current event processing
  ---- EventProcessorFailure BEGIN
    An exception occurred during current event processing
    ---- ScheduleExecutionFailure BEGIN
      ProcessingStopped.

      ---- ProductNotFound BEGIN
        A request to resolve an art::Ptr to a product containing items of type: simb::MCTruth with ProductID 1:9
        cannot be satisfied because the product cannot be found.
        The productGetter was not set -- are you trying to dereference a Ptr during mixing?
        cet::exception going through module
      ---- ProductNotFound END
      Exception going through path end_path
    ---- ScheduleExecutionFailure END
  ---- EventProcessorFailure END
---- EventProcessorFailure END
%MSG
Art has completed and will exit with status 18.

Allinea shows the problem is at line 128 of BackTracker_service.cc:

    for(size_t mc = 0; mc < fMCTruthList.size(); ++mc)
      LOG_DEBUG("BackTracker") << *(fMCTruthList.at(mc).get());