Problem with "hadd" program - Error R__unzip_header:


I have a problem while reading a merged rootfile produce from “hadd” program. The error appears when I attemp to open some histograms

Error R__unzip_header: error in header
Error in <TBufferFile::ReadVersion>: Could not find the StreamerInfo with a checksum of 0x0 for the class "TH1D" in merge_histos.root.
Error in <TBufferFile::ReadClassBuffer>: Could not find the StreamerInfo for version 0 of the class TH1D, object skipped at offset 76

During the merging process, to produce this rootfile I see no error on the output (which enclose). Yet I’ve noticed an output message that I find a bit strange: after sourcing all files (935 in total), there are some messages for the several target paths and then at some point there is a message saying

hadd Opening the next 30 files

Then a new set of messages related to target paths again appears. And then no more messages about opening the source files appear. The strange issue is that if there are 953 source files and there is the indication that 30 of them were read then what happen to the other 923 files.

Sorry for not upload the rootfile but it has 127MB I cannot create right now a shorter version because there too many histograms in it.

Any hint to explain the error?

Many thanks ins advance.

out.txt (48.9 KB)

Maybe I forgot to say the most important … when error appears I’m not able to seen the content of the histogram, the histograms are shown as zero entries histograms.

If I merge, let’s say, 100 rootfiles the problem does not appear. But I must say that I would like very much to do the merging in one-go.

I really appreciate a bit of a help :frowning:

Thanks in advence.


Hi there,

I’m facing the same problem on the following version:

  | Welcome to ROOT 6.06/06                    |
  |                                            (c) 1995-2016, The ROOT Team |
  | Built for linuxx8664gcc                                                 |
  | From heads/v6-06-00-patches@v6-06-04-66-gb9c1d82, Jul 06 2016, 18:28:55 |
  | Try '.help', '.demo', '.license', '.credits', '.quit'/'.q'              |

is there any follow-up on this?

Thanks in advance.


Can you try with v6.08/02?



I did using version:

[code] ------------------------------------------------------------
| Welcome to ROOT 6.08/02 |
| © 1995-2016, The ROOT Team |
| Built for linuxx8664gcc |
| From tag v6-08-02, 2 December 2016 |

Try ‘.help’, ‘.demo’, ‘.license’, ‘.credits’, ‘.quit’/’.q’


available on atlas cvmfs by using:

lsetup “root 6.08.02-x86_64-slc6-gcc49-opt”

and got the same issue:

[quote]Error R__unzip_header: error in header
Error R__unzip_header: error in header

It’s funny though that this does not happen for all histograms merged by hadd. It have subfolders, e.g.:

hadd Target path: user.wsfreund.data16_EvtZ.June10_2016_FastCalo_plus_Ringer_tt0001_hist_test.root:/PDFsRinger_VeryLooseLLH_Smooth_v11 hadd Target path: uuser.wsfreund.data16_EvtZ.June10_2016_FastCalo_plus_Ringer_tt0001_hist_test.root:/PDFsRinger_VeryLooseLLH_Smooth_v11/PDFsRinger_VeryLooseLLH_Smooth_v11_el_pt hadd Target path: user.wsfreund.data16_EvtZ.June10_2016_FastCalo_plus_Ringer_tt0001_hist_test.root:/PDFsRinger_VeryLooseLLH_Smooth_v11/PDFsRinger_VeryLooseLLH_Smooth_v11_el_et

The ones in the master level (PDFsRinger_VeryLooseLLH_Smooth_v11) work, but the ones in the folders (/PDFsRinger_VeryLooseLLH_Smooth_v11/PDFsRinger_VeryLooseLLH_Smooth_v11_el_pt) display the error quoted above.


Hi Werner,

Is there a way for you to make public enough of the files to reproduce the problem?


Hi Philippe,

you can find the data on afs:



Hi Philippe,

Can you reproduce the reported behavior with the samples? I have removed the samples from my public repository, if you still need them, please say so.