Could not create the Minuit2 minimizer

sprock · November 15, 2025, 1:30pm

Hello,

I installed root-6.36.04 on FreeBSD-RELEASE-13.5 as a package, i.e. I did not compile it myself from source. On invoking one of the fitting tutorial scripts like this:

root [0] .x hist032_TRatioPlot_fit_lines.C

I receive the error in the topic title, the full error being:

Warning in <ROOT::Math::FitConfig::CreateMinimizer>: Could not create the Minuit2 minimizer. Try using the minimizer Minuit                                                                    Error in <ROOT::Math::FitConfig::CreateMinimizer>: Could not create the Minuit2 minimizer                                                                                                      Error in <ROOT::Math::Fitter::DoInitMinimizer>: Minimizer cannot be created                                                                                                                    Warning in <Fit>: Abnormal termination of minimization.                                                                                                                                        <Empty FitResult>                                                                                                                                                                              Error in <TBackCompFitter::GetConfidenceIntervals>: Cannot compute confidence intervals with an invalide fit result                                                                            Error in <TBackCompFitter::GetConfidenceIntervals>: Cannot compute confidence intervals with an invalide fit result

I have checked that the relevant files exist:

/usr/local/lib/root/libMinuit.rootmap      /usr/local/lib/root/libMinuit.so.6.36.04*  /usr/local/lib/root/libMinuit2.so.6.36@    /usr/local/lib/root/libMinuit_rdict.pcm
/usr/local/lib/root/libMinuit.so@          /usr/local/lib/root/libMinuit2.rootmap     /usr/local/lib/root/libMinuit2.so.6.36.04*
/usr/local/lib/root/libMinuit.so.6.36@     /usr/local/lib/root/libMinuit2.so@         /usr/local/lib/root/libMinuit2_rdict.pcm

I have sourced thisroot.sh and checked LD_LIBRARY_PATH:

/usr/local/lib/root::/home/rmason/.local/lib

root-config –etcdir:

/usr/local/etc/root

That directory is populated:

HistFactorySchema.dtd      class.rules                gitinfo.txt                notebook/                  proof/                     system.rootauthrc          valgrind-root.supp
Makefile.arch              cling/                     helgrind-root.supp         pdg_table.txt              root.desktop               system.rootdaemonrc
RadioNuclides.txt          dictpch/                   html/                      pdg_table_update.py*       root.mimes                 system.rootrc
allDict.cxx.pch            gdb-backtrace.sh*          lsan-root.supp             plugins/                   runfirefox.sh*             valgrind-root-python.supp

I think this is a configuration issue, but I don’t know what to try next. I appreciate any help offered.

Thank you.

sprock

ROOT Version: root-6.36.04
Platform: FreeBSD-RELEASE-13.5
Compiler: Not Provided

bellenot · November 16, 2025, 9:33am

Welcome to the ROOT Forum!
As the warning is telling, it doesn’t find the Minuit2 minimizer. So you should look for /usr/local/lib/root/libMinuit2.*. if it’s not here, then it might be an issue with the package manager.
One possible solution could be to change the minimizer in a custom ${HOME}/.rootrc, as:

# Default Fitter (current choices are Minuit, Minuit2, and Fumili).
Root.Fitter:             Minuit

sprock · November 17, 2025, 12:05pm

Thank you for your response.

Unfortunately, selecting minuit in ~/.rootrc does not work: root can’t find that library either and suggests trying minuit2.

As shown in my original post, the shared libraries for minuit and minuit2 are present in the location placed on LD_LIBRARY_PATH when thisroot.sh is sourced.

Thanks again.

sprock

bellenot · November 17, 2025, 12:12pm

Oh, yes, sorry I overlooked at your original post. Then this looks weird. Maybe @moneta has an idea about what could be the issue

jonas · November 17, 2025, 10:38pm

The checks you did are already very helpful, thanks! But there is one thing that could still go wrong that you didn’t check.

Does ROOT find the right etcdir at runtime? What is the output when you run gROOT->GetEtcDir() in the ROOT interpreter?

sprock · November 18, 2025, 12:13pm

Hello,

Jonas Rembser via ROOT Forum root.discourse@cern.ch writes:

jonas
November 17

The checks you did are already very helpful, thanks! But there is one thing that could still go wrong that you didn’t check.

Does ROOT find the right etcdir at runtime? What is the output when you run gROOT->GetEtcDir() in the ROOT interpreter?

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gROOT->GetEtcDir()
(const TString &) “/usr/local/etc/root”[19]

Thank you for your help.

sprock

jonas · November 18, 2025, 1:11pm

Thanks. That looks also correct, so we have to dig deeper.

Can you run this debug macro with root -b -q debug_macro.C and paste the output here? Something seems to be going wrong with the ROOT plugin system.

void debug_macro() {

    gDebug = 3;
    auto h = gROOT->GetPluginManager()->FindHandler("ROOT::Math::Minimizer", "Minuit2");
    h->LoadPlugin();
    auto * min = (ROOT::Math::Minimizer *)( h->ExecPlugin(1,"migrad" ) );
    std::cout << min << std::endl;
}

sprock · November 18, 2025, 2:57pm

Hi Jonas,

Jonas Rembser via ROOT Forum root.discourse@cern.ch writes:

jonas
November 18

Thanks. That looks also correct, so we have to dig deeper.

Can you run this debug macro with root -b -q debug_macro.C and paste the output here? Something seems to be going wrong with
the ROOT plugin system.

Processing debug_macro.C…
Info in TPluginManager::FindHandler: did not find plugin for class ROOT::Math::Minimizer and uri Minuit2
Error in : Trying to dereference null pointer or trying to call routine taking non-null arguments
Execution of your code was aborted.
In file included from input_line_8:1:
/usr/home/rmason/Help/FreeBSD/debug_macro.C:5:5: warning: null passed to a callee that requires a non-null argument [-Wnonnull]
h->LoadPlugin();

Thanks again,
sprock

sprock · April 27, 2026, 3:47pm

I still have the same problem. I now have root-6.38.00 installed.

Wile_E_Coyote · April 27, 2026, 6:27pm

In your original post, I can see the files “/usr/local/lib/root/libMinuit*.rootmap” and “/usr/local/lib/root/libMinuit*_rdict.pcm”. It seems to me that these files were present in ROOT 6.18 and earlier. In newer versions, you should only have the “Minuit.pcm” and “Minuit2.pcm” files. So, you may have “mixed” ROOT distributions. Try to uninstall all currently installed ROOT versions, completely remove (at least) the directories “/usr/local/lib/root” and “/usr/local/etc/root”, and then reinstall your new ROOT version.

sprock · April 28, 2026, 9:27am

Thanks for the advice.

I have done as you suggest, but to no avail, unfortunately.

Wile_E_Coyote · April 28, 2026, 9:32am

Try:
echo ROOTSYS is ${ROOTSYS}
root-config --bindir
which -a root
ldd $(root-config --bindir)/root
which -a root.exe
ldd $(root-config --bindir)/root.exe
root-config --etcdir
root-config --libdir
ls -al $(root-config --libdir)/*Minuit*
ldd $(root-config --libdir)/libMinuit2.so

BTW. Make sure you do not have any “${HOME}/.rootrc”, “${HOME}/rootlogon.C”, “${HOME}/.rootlogon.C” files.