Dear MadGraph, This is a follow-up to https://answers.launchpad.net/mg5amcnlo/+question/696199 As mentioned earlier, have taken the heavyN FeynRules model and added a dim-5 dipole operator. In MadGraph v2.7.3, I can execute the following command without a problem: import model heavyNeff4_UFO --modelname generate n5 > all all output Test1 I then go to Test1 and run MadEvent, executing calculate_decay_widths . The code works, and I get a result. If I do the same in MadGraph v2.9.2, there is a problem when executing "output Test1", with MadGraph crashing: MG5_aMC>output Test1 INFO: initialize a new directory: Test1 INFO: remove old information in Test1 INFO: Generating Helas calls for process: n5 > ve z QNP<=2 @1 INFO: Processing color information for process: n5 > ve z QNP<=2 @1 INFO: Generating Helas calls for process: n5 > vm z QNP<=2 @1 INFO: Reusing existing color information for process: n5 > vm z QNP<=2 @1 INFO: Generating Helas calls for process: n5 > vt z QNP<=2 @1 INFO: Reusing existing color information for process: n5 > vt z QNP<=2 @1 INFO: Generating Helas calls for process: n5 > a ve QNP<=2 @1 INFO: Processing color information for process: n5 > a ve QNP<=2 @1 INFO: Generating Helas calls for process: n5 > a vm QNP<=2 @1 INFO: Reusing existing color information for process: n5 > a vm QNP<=2 @1 INFO: Generating Helas calls for process: n5 > a vt QNP<=2 @1 INFO: Reusing existing color information for process: n5 > a vt QNP<=2 @1 INFO: Generating Helas calls for process: n5 > a n4 QNP<=2 @1 INFO: Reusing existing color information for process: n5 > a n4 QNP<=2 @1 INFO: Generating Helas calls for process: n5 > a n6 QNP<=2 @1 INFO: Reusing existing color information for process: n5 > a n6 QNP<=2 @1 INFO: Generating Helas calls for process: n5 > ve h QNP<=2 @1 INFO: Reusing existing color information for process: n5 > ve h QNP<=2 @1 INFO: Generating Helas calls for process: n5 > vm h QNP<=2 @1 INFO: Reusing existing color information for process: n5 > vm h QNP<=2 @1 INFO: Generating Helas calls for process: n5 > vt h QNP<=2 @1 INFO: Reusing existing color information for process: n5 > vt h QNP<=2 @1 INFO: Generating Helas calls for process: n5 > e- w+ QNP<=2 @1 INFO: Reusing existing color information for process: n5 > e- w+ QNP<=2 @1 INFO: Generating Helas calls for process: n5 > mu- w+ QNP<=2 @1 INFO: Reusing existing color information for process: n5 > mu- w+ QNP<=2 @1 INFO: Generating Helas calls for process: n5 > ta- w+ QNP<=2 @1 INFO: Reusing existing color information for process: n5 > ta- w+ QNP<=2 @1 INFO: Generating Helas calls for process: n5 > e+ w- QNP<=2 @1 INFO: Reusing existing color information for process: n5 > e+ w- QNP<=2 @1 INFO: Generating Helas calls for process: n5 > mu+ w- QNP<=2 @1 INFO: Reusing existing color information for process: n5 > mu+ w- QNP<=2 @1 INFO: Generating Helas calls for process: n5 > ta+ w- QNP<=2 @1 INFO: Reusing existing color information for process: n5 > ta+ w- QNP<=2 @1 INFO: Generating Helas calls for process: n5 > z n4 QNP<=2 @1 INFO: Reusing existing color information for process: n5 > z n4 QNP<=2 @1 INFO: Generating Helas calls for process: n5 > z n6 QNP<=2 @1 INFO: Reusing existing color information for process: n5 > z n6 QNP<=2 @1 INFO: Generating Helas calls for process: n5 > h n4 QNP<=2 @1 INFO: Reusing existing color information for process: n5 > h n4 QNP<=2 @1 INFO: Generating Helas calls for process: n5 > h n5 QNP<=2 @1 INFO: Reusing existing color information for process: n5 > h n5 QNP<=2 @1 INFO: Generating Helas calls for process: n5 > h n6 QNP<=2 @1 INFO: Reusing existing color information for process: n5 > h n6 QNP<=2 @1 INFO: Creating files in directory P1_n5_vez INFO: Generating Feynman diagrams for Process: n5 > ve z QNP<=2 @1 INFO: Creating files in directory P1_n5_vmz INFO: Generating Feynman diagrams for Process: n5 > vm z QNP<=2 @1 INFO: Creating files in directory P1_n5_vtz INFO: Generating Feynman diagrams for Process: n5 > vt z QNP<=2 @1 INFO: Creating files in directory P1_n5_ave INFO: Generating Feynman diagrams for Process: n5 > a ve QNP<=2 @1 INFO: Creating files in directory P1_n5_avm INFO: Generating Feynman diagrams for Process: n5 > a vm QNP<=2 @1 INFO: Creating files in directory P1_n5_avt INFO: Generating Feynman diagrams for Process: n5 > a vt QNP<=2 @1 INFO: Creating files in directory P1_n5_an4 INFO: Generating Feynman diagrams for Process: n5 > a n4 QNP<=2 @1 INFO: Creating files in directory P1_n5_an6 INFO: Generating Feynman diagrams for Process: n5 > a n6 QNP<=2 @1 INFO: Creating files in directory P1_n5_veh INFO: Generating Feynman diagrams for Process: n5 > ve h QNP<=2 @1 INFO: Creating files in directory P1_n5_vmh INFO: Generating Feynman diagrams for Process: n5 > vm h QNP<=2 @1 INFO: Creating files in directory P1_n5_vth INFO: Generating Feynman diagrams for Process: n5 > vt h QNP<=2 @1 INFO: Creating files in directory P1_n5_emwp INFO: Generating Feynman diagrams for Process: n5 > e- w+ QNP<=2 @1 INFO: Creating files in directory P1_n5_mumwp INFO: Generating Feynman diagrams for Process: n5 > mu- w+ QNP<=2 @1 INFO: Creating files in directory P1_n5_tamwp INFO: Generating Feynman diagrams for Process: n5 > ta- w+ QNP<=2 @1 INFO: Creating files in directory P1_n5_epwm INFO: Generating Feynman diagrams for Process: n5 > e+ w- QNP<=2 @1 INFO: Creating files in directory P1_n5_mupwm INFO: Generating Feynman diagrams for Process: n5 > mu+ w- QNP<=2 @1 INFO: Creating files in directory P1_n5_tapwm INFO: Generating Feynman diagrams for Process: n5 > ta+ w- QNP<=2 @1 INFO: Creating files in directory P1_n5_zn4 INFO: Generating Feynman diagrams for Process: n5 > z n4 QNP<=2 @1 INFO: Creating files in directory P1_n5_zn6 INFO: Generating Feynman diagrams for Process: n5 > z n6 QNP<=2 @1 INFO: Creating files in directory P1_n5_hn4 INFO: Generating Feynman diagrams for Process: n5 > h n4 QNP<=2 @1 INFO: Creating files in directory P1_n5_hn5 INFO: Generating Feynman diagrams for Process: n5 > h n5 QNP<=2 @1 INFO: Creating files in directory P1_n5_hn6 INFO: Generating Feynman diagrams for Process: n5 > h n6 QNP<=2 @1 Generated helas calls for 22 subprocesses (25 diagrams) in 0.023 s Wrote files for 91 helas calls in 0.399 s Fatal Python error: _Py_CheckRecursiveCall: Cannot recover from stack overflow. 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[jjones@arrakis MG5_aMC_v2_9_2]$ Any clues to what might be happening?

MadGraph5_aMC@NLO

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