Then this must be an issue in the Geant4 re-implementation of ROOT I/O. This sounds like the same as here: Opening a file in update mode causes Error in <TBasket::Streamer>: The value of fNbytes is incorrect - #15 by pcanal
Then this must be an issue in the Geant4 re-implementation of ROOT I/O. This sounds like the same as here: Opening a file in update mode causes Error in <TBasket::Streamer>: The value of fNbytes is incorrect - #15 by pcanal