FitFCN simultaneous fit results depends on ROOT version


I am using ROOT::Fit::Fitter to do a simultaneous fit of my experimental data.

At root 5.34/11 it gives an error: “Invalid FitResult (status = 4 )”, but fit very well and I an happy with the results. However, by moving to a new root version (5.34/34) I found that additional to the same error, fit returns inf Chi2 and fit results do not describe experimental data at all.

Do You have any ideas where the problem can be? How I can run my fit in a new ROOT version?

Many thanks for your time!

Best regards,


Can you try maybe with a latest ROOT 6 version ? If in this case also fails, I would need your running program to debug your problem

Best Regards