I try to rewrite some root files generated by newer version of ROOT (for example 6.14) with an older veresion of ROOT (5.xx)
I store a simple TTree (with some casual data) in the originial root file (of ROOT 6). Only for testing. Then open it with ROOT 5. All data of the TTree can be loaded correctly. But a warning is shown as:
Warning in <TStreamerInfo::BuildCheck>: The StreamerInfo of class TAttMarker read from file test.root has the same version (=2) as the active class but a different checksum. You should update the version to ClassDef(TAttMarker,3). Do not try to write objects with the current class definition, the files will not be readable.
I want to write the TTree object to a new root file (by ROOT 5). But the message warning that first I should “update the version to ClassDef…”
So, how can I get rid of this warning and correctly write a copy of the TTree object to a new file with ROOT 5?