We’re currently using ROOT v5.18c. One of our colleagues was attempting to read one of our ntuples (all the branches are simple data types) using ROOT v5.16, and received this warning:
Warning in TStreamerInfo::BuildCheck:
The StreamerInfo of class TBranch read from file
data/r0236102471_v000_merit.root
has the same version (=10) as the active class but a different checksum.
You should update the version to ClassDef(TBranch,11).
Do not try to write objects with the current class definition,
the files will not be readable
I looked at the include file for TBranch.h in ROOT v5.14d (it’s what I had around) versus TBranch.h in 5.18c. I see that there are two additional data members - does the version need to be incremented?
I’m assuming that despite this warning - one could still read our ntuples with an earlier version of ROOT - but should not, as the warning says attempt to write. Right?
Hi Philippe,
hmm…well then I don’t understand the problem but here is a one event ntuple created with ROOT v5.18c. When I open this file in ROOT v5.16.00, I received the following message:
root [0] TFile f(“small.root”,“READ”)
Warning in TStreamerInfo::BuildCheck:
The StreamerInfo of class TBranch read from file small.root
has the same version (=10) as the active class but a different checksum.
You should update the version to ClassDef(TBranch,11).
Do not try to write objects with the current class definition,
the files will not be readable.