Problem with TBrowser on a Mac


I’m having a problem with ROOT 6.12/06 on a Mac. After working fine for several years, TBrowser stopped working. I could still pop up a TBrowser window, and can click on it, select a file and then a variable in a TTree to histogram. Unfortunately, no histogram ever comes up. There was no crash or anything, just no action in the plot window. This was for modest sized (1000 entries) TTrees, so there should be no memory issues.

This was on a MacBook Pro running High Sierra, with an older version of Xcode. So,I thought that the first thing to do was to upgrade, so I upgraded to Catalina (LBNL warned us that there were issues with Big Sur, but Catalina is pretty new) and then Xcode 12.3. Unfortunately, I get the same behavior, whether Quartz is running or not. I thought it might be a general graphics problem, but when I copied the ROOT CandleDecay example ( into a file and ran it, it worked fine, with the expected graphics output. So, this seems somehow specific to TBrowser. I did look through the forums, and found some reports of TBrowser problems on a Mac, but nothing that matched this. And, many of them seemed very old, and, unfortunately with somewhat unclear resolution.

I am also not sure if this is a Mac-only problem.

Any suggestions would be appreciated.


_ROOT Version: 6.12/06
Platform: Mac High Sierra and then Catalina
_Compiler: XCode older version and then 12.3.

I just tried with ROOT master on Mac running Big Sur using the hsimple.root file generated by $ROOTSYS/tutorials/hsimple.C and it do not the the issue you are describing. When I double click on a tree variable I see the plot.

That’s indeed very curious; we have never seen something like this. What does happen here:

$ root
root [0] TH1F h;
root [1] h.Draw();

Can you post a screenshot?

Hi Axel:

It works as expected (see screenshot).

I have been continuing to try to understand the problem; it may be that there was a problem with the TTree that I was trying to look at with the TBrowser, rather than a problem with TBrowser itself.


Can you try to access this tree outside TBrowser ?


Hi Oliver,

I am not sure. I had eventually decided that this was likely due to a problem caused by an automatic update to my operating system (I was probably grasping at straws, but…), so I updated my MacOS from High Sierra to Catalina. Then I updated my Xtools to 12.3. This introduced C++ 11 language constraints, with ASSERT no longer working. So, I had to update the code that made the NTuple. After that was done, everything worked. So, things are fixed, but I am not sure at this point what caused the original problrm. But, it seems likely that there was indeed a problem with the TTree.

Many thanks for your help.


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