Byte count mismatch and TPaletteAxis::Streamer

[maszyman]

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Description

Probably after #20187 reading files containing TPaletteAxis objects triggers byte count mismatch errors and warnings like:

14:55:09 TBufferFile::CheckByteCount                         ERROR object of class TPaletteAxis read too many bytes: 343 instead of 339
14:55:09 TBufferFile::CheckByteCount                       WARNING TPaletteAxis::Streamer() not in sync with data on file /cvmfs/atlas.cern.ch/repo/sw/database/GroupData/JetUncertainties/CalibArea-08/rel22/Winter2025_PreRec/R4_AllComponents.root, fix Streamer()
14:55:09 TBufferFile::CheckByteCount                         ERROR object of class TPaletteAxis read too many bytes: 346 instead of 342
14:55:09 TBufferFile::CheckByteCount                       WARNING TPaletteAxis::Streamer() not in sync with data on file /cvmfs/atlas.cern.ch/repo/sw/database/GroupData/JetUncertainties/CalibArea-08/rel22/Winter2025_PreRec/R4_AllComponents.root, fix Streamer()
14:55:09 TBufferFile::CheckByteCount                         ERROR object of class TPaletteAxis read too many bytes: 319 instead of 315
14:55:09 TBufferFile::CheckByteCount                       WARNING TPaletteAxis::Streamer() not in sync with data on file /cvmfs/atlas.cern.ch/repo/sw/database/GroupData/JetUncertainties/CalibArea-08/rel22/Winter2025_PreRec/R4_AllComponents.root, fix Streamer()
14:55:09 TBufferFile::CheckByteCount                         ERROR object of class TPaletteAxis read too many bytes: 308 instead of 304
14:55:09 TBufferFile::CheckByteCount                       WARNING TPaletteAxis::Streamer() not in sync with data on file /cvmfs/atlas.cern.ch/repo/sw/database/GroupData/JetUncertainties/CalibArea-08/rel22/Winter2025_PreRec/R4_AllComponents.root, fix Streamer()
14:55:09 TBufferFile::CheckByteCount                         ERROR object of class TPaletteAxis read too many bytes: 308 instead of 304
14:55:09 TBufferFile::CheckByteCount                       WARNING TPaletteAxis::Streamer() not in sync with data on file /cvmfs/atlas.cern.ch/repo/sw/database/GroupData/JetUncertainties/CalibArea-08/rel22/Winter2025_PreRec/R4_AllComponents.root, fix Streamer()
14:55:09 TBufferFile::CheckByteCount                         ERROR object of class TPaletteAxis read too many bytes: 308 instead of 304
14:55:09 TBufferFile::CheckByteCount                       WARNING TPaletteAxis::Streamer() not in sync with data on file /cvmfs/atlas.cern.ch/repo/sw/database/GroupData/JetUncertainties/CalibArea-08/rel22/Winter2025_PreRec/R4_AllComponents.root, fix Streamer()

It looks like TPaletteAxis gained a new data member (Int_t fLog) without backward-compatibility handling.

Reproducer

» root -l /cvmfs/atlas.cern.ch/repo/sw/database/GroupData/JetUncertainties/CalibArea-08/rel22/Winter2025_PreRec/R4_AllComponents.root                                             maszyman@aiatlasbm004
root [0] 
Attaching file /cvmfs/atlas.cern.ch/repo/sw/database/GroupData/JetUncertainties/CalibArea-08/rel22/Winter2025_PreRec/R4_AllComponents.root as _file0...
Warning in <TStreamerInfo::BuildCheck>: 
   The StreamerInfo of class TPaletteAxis read from file /cvmfs/atlas.cern.ch/repo/sw/database/GroupData/JetUncertainties/CalibArea-08/rel22/Winter2025_PreRec/R4_AllComponents.root
   has the same version (=4) as the active class but a different checksum.
   You should update the version to ClassDef(TPaletteAxis,5).
   Do not try to write objects with the current class definition,
   the files will not be readable.

Warning in <TStreamerInfo::CompareContent>: The following data member of
the in-memory layout version 4 of class 'TPaletteAxis' is missing from 
the on-file layout version 4:
   int fLog; //
(TFile *) 0x3153200

ROOT version

master

Installation method

dev3

Operating system

Linux

Additional context

No response

[couet]

Thanks for the report. You are right I forgot to increment the verison number

[github-actions]

Hi @couet,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖