I am trying to open a root file containing a rooworkspace, but I get the error Warning in <TClass::Init>: no dictionary for class RooSTLRefCountList<RooAbsArg> is available. The root version I am using is ROOT 6.02/05. I was able to open the file without any issue in ROOT 6.18/00. Unfortunately the analysis framework I am using uses ROOT 6.02/05. Could you please suggest a solution for this?
There were some major updates in RooFit in ROOT version 6.18, and the workspaces “from the future” cannot be read with ROOT versions from the past. There are three possible solutions:
Update to ROOT 6.18, but that’s obviously not possible in your case.
Have the people write out the workspace with ROOT 6.16 or earlier.
Ask for the code to produce the workspace, and generate it yourself.