Please use the mlr add-on code https://github.com/HeidiSeibold/sandbox/blob/master/rstuff/openml_newctree/new_ctree_mlr.R and devel partykit package revision 1089: https://r-forge.r-project.org/scm/viewvc.php/pkg/devel/?root=partykit 3 0 8 mlr.classif.develpartykit.cforest 5482 mlr.classif.develpartykit.cforest R_3.3.2-v2.d3517482 public 0 2017-01-08T10:21:41Z R_3.3.2, OpenML_1.1, mlr_2.10, partykit_2.0.1