Old ROOT open ROOT file created by new version of ROOT

ROOT
3

You can either:

  • Download the tip of the v6-24-00-patches branch and build that version of ROOT

or

  • Disable the new behavior when writing the files, by to calling file->SetBit(TFile::k630forwardCompatibility);. Alternatively The rootrc key TFile.v630forwardCompatibility can be used to change the default to have the bit set for all TFiles