Failure to reduce color indices in model SMEFTsim_topU3l_MwScheme_UFO

[zeniheisser]

Runtime error while unweighting in model SMEFTsim_topU3l_MwScheme_UFO.

Minimal working example:

import model SMEFTsim_topU3l_MwScheme_UFO-massless
generate g u > t t~ t t~ u
output madevent_simd
launch

Fails due to lack of results:

generate_events run_01
Traceback (most recent call last):
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/interface/extended_cmd.py", line 1548, in onecmd
    return self.onecmd_orig(line, **opt)
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/interface/extended_cmd.py", line 1497, in onecmd_orig
    return func(arg, **opt)
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/interface/madevent_interface.py", line 2406, in do_generate_events
    self.run_generate_events(switch_mode, args)
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/interface/common_run_interface.py", line 7897, in new_fct
    scan_over_run_card(original_fct, obj, *args, **opts)
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/interface/common_run_interface.py", line 7829, in scan_over_run_card
    return original_fct(obj, *args, **opts)
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/interface/madevent_interface.py", line 2603, in run_generate_events
    self.exec_cmd('refine %s' % nb_event, postcmd=False)
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/interface/extended_cmd.py", line 1577, in exec_cmd
    stop = Cmd.onecmd_orig(current_interface, line, **opt)
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/interface/extended_cmd.py", line 1497, in onecmd_orig
    return func(arg, **opt)
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/interface/madevent_interface.py", line 3610, in do_refine
    x_improve.launch() # create the ajob for the refinment.
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/madevent/gen_ximprove.py", line 1082, in launch
    self.results = sum_html.collect_result(self.cmd,
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/madevent/sum_html.py", line 753, in collect_result
    P_comb.add_results(os.path.basename(G), path, mfactors[G])
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/madevent/sum_html.py", line 434, in add_results
    oneresult.read_results(filepath)
  File "/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/madgraph/madevent/sum_html.py", line 281, in read_results
    finput = open(filepath)
FileNotFoundError: [Errno 2] No such file or directory: '/data/zwetters/gpucpp/MG5aMC/mg5amcnlo/PROC_SMEFTsim_topU3l_MwScheme_UFO-massless_1/SubProcesses/P1_uux_tttxtxg/G2/results.dat'
Related File: /data/zwetters/gpucpp/MG5aMC/mg5amcnlo/PROC_SMEFTsim_topU3l_MwScheme_UFO-massless_1/SubProcesses/P1_uux_tttxtxg/G2/results.dat

G2/log.txt

 Ranmar initialization seeds       31060        9398
  Particle       3       4       5       6       7
      Et >     0.0     0.0     0.0     0.0    20.0
       E >     0.0     0.0     0.0     0.0     0.0
     Eta <    -1.0    -1.0    -1.0    -1.0     5.0
   xqcut:      0.0     0.0     0.0     0.0     0.0
d R # 3  >    -0.0     0.0     0.0     0.0     0.0
d R # 4  >    -0.0    -0.0     0.0     0.0     0.0
d R # 5  >    -0.0    -0.0    -0.0     0.0     0.0
d R # 6  >    -0.0    -0.0    -0.0    -0.0     0.0
s min # 3>     0.0119384.1119384.1119384.1     0.0
s min # 4>     0.0     0.0119384.1119384.1     0.0
s min # 5>     0.0     0.0     0.0119384.1     0.0
s min # 6>     0.0     0.0     0.0     0.0     0.0
xqcutij # 3>     0.0     0.0     0.0     0.0     0.0
xqcutij # 4>     0.0     0.0     0.0     0.0     0.0
xqcutij # 5>     0.0     0.0     0.0     0.0     0.0
xqcutij # 6>     0.0     0.0     0.0     0.0     0.0
 No cut BW           -3           1
 NGOODHEL =          64
 NCOMB =         128
 MULTI_CHANNEL = TRUE
 CHANNEL_ID =           4
 Error: failed to reduce to color indices:            1           1

ls status:
input_app.txt
run1_app.log

This occurs for several but not all G directories:

$ grep -irn "Error: failed to reduce to color indices"
G12/run1_app.log:433: Error: failed to reduce to color indices:            0           1
G12/log.txt:433: Error: failed to reduce to color indices:            0           1
G10/run1_app.log:432: Error: failed to reduce to color indices:            0           1
G10/log.txt:432: Error: failed to reduce to color indices:            0           1
G31/run1_app.log:433: Error: failed to reduce to color indices:            1           1
G31/log.txt:433: Error: failed to reduce to color indices:            1           1
grep: addmothers.o: binary file matches
G74/run1_app.log:432: Error: failed to reduce to color indices:            0           1
G74/log.txt:432: Error: failed to reduce to color indices:            0           1
G85/run1_app.log:433: Error: failed to reduce to color indices:            0           1
G85/log.txt:433: Error: failed to reduce to color indices:            0           1
G5/run1_app.log:432: Error: failed to reduce to color indices:            1           1
G5/log.txt:432: Error: failed to reduce to color indices:            1           1
G7/run1_app.log:431: Error: failed to reduce to color indices:            1           1
G7/log.txt:431: Error: failed to reduce to color indices:            1           1
G71/run1_app.log:433: Error: failed to reduce to color indices:            0           1
G71/log.txt:433: Error: failed to reduce to color indices:            0           1
G9/run1_app.log:431: Error: failed to reduce to color indices:            1           1
G9/log.txt:431: Error: failed to reduce to color indices:            1           1
G88/run1_app.log:432: Error: failed to reduce to color indices:            0           1
G88/log.txt:432: Error: failed to reduce to color indices:            0           1
G2/run1_app.log:432: Error: failed to reduce to color indices:            1           1
G2/log.txt:432: Error: failed to reduce to color indices:            1           1
grep: madevent_cuda: binary file matches

[zeniheisser]

UPDATE: Not a model-specific issue, also happens for the standard model:

$./bin/mg5_aMC
$generate p p > t t~ t t~ j
$output madevent_simd
$launch

Debug:

#************************************************************
#*               MadGraph5_aMC@NLO/MadEvent                 *
#*                                                          *
#*                *                       *                 *
#*                  *        * *        *                   *
#*                    * * * * 5 * * * *                     *
#*                  *        * *        *                   *
#*                *                       *                 *
#*                                                          *
#*                                                          *
#*         VERSION 3.6.3                 2025-06-12         *
#*                                                          *
#*    The MadGraph5_aMC@NLO Development Team - Find us at   *
#*    https://server06.fynu.ucl.ac.be/projects/madgraph     *
#*                                                          *
#************************************************************
#*                                                          *
#*               Command File for MadEvent                  *
#*                                                          *
#*     run as ./bin/madevent.py filename                    *
#*                                                          *
#************************************************************
generate_events run_01
Traceback (most recent call last):
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/interface/extended_cmd.py", line 1548, in onecmd
    return self.onecmd_orig(line, **opt)
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/interface/extended_cmd.py", line 1497, in onecmd_orig
    return func(arg, **opt)
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/interface/madevent_interface.py", line 2406, in do_generate_events
    self.run_generate_events(switch_mode, args)
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/interface/common_run_interface.py", line 7897, in new_fct
    scan_over_run_card(original_fct, obj, *args, **opts)
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/interface/common_run_interface.py", line 7829, in scan_over_run_card
    return original_fct(obj, *args, **opts)
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/interface/madevent_interface.py", line 2585, in run_generate_events
    self.exec_cmd('survey  %s %s' % \
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/interface/extended_cmd.py", line 1577, in exec_cmd
    stop = Cmd.onecmd_orig(current_interface, line, **opt)
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/interface/extended_cmd.py", line 1497, in onecmd_orig
    return func(arg, **opt)
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/interface/madevent_interface.py", line 3499, in do_survey
    cross, error = self.make_make_all_html_results()
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/interface/common_run_interface.py", line 754, in make_make_all_html_results
    return sum_html.make_all_html_results(self, folder_names, jobs, get_attr)
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/madevent/sum_html.py", line 781, in make_all_html_results
    Presults = collect_result(cmd, folder_names=folder_names, jobs=jobs)
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/madevent/sum_html.py", line 753, in collect_result
    P_comb.add_results(os.path.basename(G), path, mfactors[G])
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/madevent/sum_html.py", line 434, in add_results
    oneresult.read_results(filepath)
  File "/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/madgraph/madevent/sum_html.py", line 281, in read_results
    finput = open(filepath)
FileNotFoundError: [Errno 2] No such file or directory: '/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/4t_1j/SubProcesses/P1_gg_tttxtxg/G7/results.dat'
Related File: /home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/4t_1j/SubProcesses/P1_gg_tttxtxg/G7/results.dat
                              Run Options    
                              -----------    
               stdout_level 	:	20 (user set)

                         MadEvent Options    
                         ----------------    
     automatic_html_opening 	:	False (user set)
        notification_center 	:	True
                   run_mode 	:	2
              cluster_queue 	:	None (user set)
               cluster_time 	:	None (user set)
               cluster_size 	:	100
             cluster_memory 	:	100 (user set)
                    nb_core 	:	8 (user set)
          cluster_temp_path 	:	None

                      Configuration Options    
                      ---------------------    
               pythia8_path 	:	/home/zwetters/MG5_aMC_v3.6.3/MG5_aMC_v3_6_3/HEPTools/pythia8 (user set)
                  hwpp_path 	:	None (user set)
                thepeg_path 	:	None (user set)
                 hepmc_path 	:	None (user set)
           madanalysis_path 	:	None (user set)
          madanalysis5_path 	:	None (user set)
            pythia-pgs_path 	:	None (user set)
                    td_path 	:	None (user set)
               delphes_path 	:	None (user set)
        exrootanalysis_path 	:	None (user set)
               syscalc_path 	:	None (user set)
                 rivet_path 	:	None
                  yoda_path 	:	None
                     lhapdf 	:	lhapdf-config
                 lhapdf_py2 	:	None
                 lhapdf_py3 	:	None
                    timeout 	:	60
              f2py_compiler 	:	None
          f2py_compiler_py2 	:	None
          f2py_compiler_py3 	:	None
                web_browser 	:	None
                 eps_viewer 	:	None
                text_editor 	:	None
           fortran_compiler 	:	None
               cpp_compiler 	:	None
                auto_update 	:	7 (user set)
               cluster_type 	:	condor
      cluster_status_update 	:	(600, 30)
           cluster_nb_retry 	:	1
         cluster_local_path 	:	None
         cluster_retry_wait 	:	300
#************************************************************
#*                     MadGraph5_aMC@NLO                    *
#*                                                          *
#*                *                       *                 *
#*                  *        * *        *                   *
#*                    * * * * 5 * * * *                     *
#*                  *        * *        *                   *
#*                *                       *                 *
#*                                                          *
#*                                                          *
#*         VERSION 3.6.3                 2025-06-12         *
#*                                                          *
#*    The MadGraph5_aMC@NLO Development Team - Find us at   *
#*    https://server06.fynu.ucl.ac.be/projects/madgraph     *
#*                                                          *
#************************************************************
#*                                                          *
#*               Command File for MadGraph5_aMC@NLO         *
#*                                                          *
#*     run as ./bin/mg5_aMC  filename                       *
#*                                                          *
#************************************************************
set group_subprocesses Auto
set ignore_six_quark_processes False
set low_mem_multicore_nlo_generation False
set complex_mass_scheme False
set include_lepton_initiated_processes False
set gauge unitary
set loop_optimized_output True
set loop_color_flows False
set max_npoint_for_channel 0
set default_unset_couplings 99
set max_t_for_channel 99
set zerowidth_tchannel True
set nlo_mixed_expansion True
import model sm
define p = g u c d s u~ c~ d~ s~
define j = g u c d s u~ c~ d~ s~
define l+ = e+ mu+
define l- = e- mu-
define vl = ve vm vt
define vl~ = ve~ vm~ vt~
generate 2p > 2t 2t~ 1j
output madevent_simd 4t_1j
######################################################################
## PARAM_CARD AUTOMATICALY GENERATED BY MG5                       ####
######################################################################
###################################
## INFORMATION FOR MASS
###################################
BLOCK MASS # 
      5 4.700000e+00 # mb
      6 1.730000e+02 # mt
      15 1.777000e+00 # mta
      23 9.118800e+01 # mz
      25 1.250000e+02 # mh
      1 0.000000e+00 # d : 0.0
      2 0.000000e+00 # u : 0.0
      3 0.000000e+00 # s : 0.0
      4 0.000000e+00 # c : 0.0
      11 0.000000e+00 # e- : 0.0
      12 0.000000e+00 # ve : 0.0
      13 0.000000e+00 # mu- : 0.0
      14 0.000000e+00 # vm : 0.0
      16 0.000000e+00 # vt : 0.0
      21 0.000000e+00 # g : 0.0
      22 0.000000e+00 # a : 0.0
      24 8.041900e+01 # w+ : cmath.sqrt(mz__exp__2/2. + cmath.sqrt(mz__exp__4/4. - (aew*cmath.pi*mz__exp__2)/(gf*sqrt__2)))
###################################
## INFORMATION FOR SMINPUTS
###################################
BLOCK SMINPUTS # 
      1 1.325070e+02 # aewm1
      2 1.166390e-05 # gf
      3 1.300000e-01 # as (note: this parameter is not used if you use a pdf set)
###################################
## INFORMATION FOR YUKAWA
###################################
BLOCK YUKAWA # 
      5 4.700000e+00 # ymb
      6 1.730000e+02 # ymt
      15 1.777000e+00 # ymtau
###################################
## INFORMATION FOR DECAY
###################################
DECAY 6 1.491500e+00 # wt
DECAY 23 2.441404e+00 # wz
DECAY 24 2.047600e+00 # ww
DECAY 25 6.382339e-03 # wh
DECAY 1 0.000000e+00 # d : 0.0
DECAY 2 0.000000e+00 # u : 0.0
DECAY 3 0.000000e+00 # s : 0.0
DECAY 4 0.000000e+00 # c : 0.0
DECAY 5 0.000000e+00 # b : 0.0
DECAY 11 0.000000e+00 # e- : 0.0
DECAY 12 0.000000e+00 # ve : 0.0
DECAY 13 0.000000e+00 # mu- : 0.0
DECAY 14 0.000000e+00 # vm : 0.0
DECAY 15 0.000000e+00 # ta- : 0.0
DECAY 16 0.000000e+00 # vt : 0.0
DECAY 21 0.000000e+00 # g : 0.0
DECAY 22 0.000000e+00 # a : 0.0

#*********************************************************************
#                       MadGraph5_aMC@NLO                            *
#                                                                    *
#                     run_card.dat MadEvent                          *
#                                                                    *
#  This file is used to set the parameters of the run.               *
#                                                                    *
#  Some notation/conventions:                                        *
#                                                                    *
#   Lines starting with a '# ' are info or comments                  *
#                                                                    *
#   mind the format:   value    = variable     ! comment             *
#                                                                    *
#   To display more options, you can type the command:               *
#      update to_full                                                *
#*********************************************************************
#                                                                    
#*********************************************************************
# Tag name for the run (one word)                                    *
#*********************************************************************
  tag_1	= run_tag ! name of the run 
#*********************************************************************
# Number of events and rnd seed                                      *
# Warning: Do not generate more than 1M events in a single run       *
#*********************************************************************
  10000	= nevents ! Number of unweighted events requested 
  0	= iseed ! rnd seed (0=assigned automatically=default))
#*********************************************************************
# Collider type and energy                                           *
# lpp: 0=No PDF, 1=proton, -1=antiproton,                            *
#                2=elastic photon of proton/ion beam                 *
#             +/-3=PDF of electron/positron beam                     *
#             +/-4=PDF of muon/antimuon beam                         *
#*********************************************************************
  1	= lpp1 ! beam 1 type 
  1	= lpp2 ! beam 2 type
  6500.0	= ebeam1 ! beam 1 total energy in GeV
  6500.0	= ebeam2 ! beam 2 total energy in GeV
# To see polarised beam options: type "update beam_pol"

#*********************************************************************
# PDF CHOICE: this automatically fixes alpha_s and its evol.         *
# pdlabel: lhapdf=LHAPDF (installation needed) [1412.7420]           *
#          iww=Improved Weizsaecker-Williams Approx.[hep-ph/9310350] *
#          eva=Effective W/Z/A Approx.       [2111.02442]            *
#          edff=EDFF in gamma-UPC            [eq.(11) in 2207.03012] *
#          chff=ChFF in gamma-UPC            [eq.(13) in 2207.03012] *
#          none=No PDF, same as lhapdf with lppx=0                   *
#*********************************************************************
  nn23lo1	= pdlabel ! PDF set 
  230000	= lhaid ! if pdlabel=lhapdf, this is the lhapdf number
# To see heavy ion options: type "update ion_pdf"
#*********************************************************************
# Renormalization and factorization scales                           *
#*********************************************************************
  False	= fixed_ren_scale ! if .true. use fixed ren scale
  False	= fixed_fac_scale ! if .true. use fixed fac scale
  91.188	= scale ! fixed ren scale
  91.188	= dsqrt_q2fact1 ! fixed fact scale for pdf1
  91.188	= dsqrt_q2fact2 ! fixed fact scale for pdf2
  -1	= dynamical_scale_choice ! Choose one of the preselected dynamical choices
  1.0	= scalefact ! scale factor for event-by-event scales

 
#*********************************************************************
# Type and output format
#*********************************************************************
  True	= gridpack !True = setting up the grid pack
  -1.0	= time_of_flight ! threshold (in mm) below which the invariant livetime is not written (-1 means not written)
  average	= event_norm ! average/sum. Normalization of the weight in the LHEF
# To see MLM/CKKW  merging options: type "update MLM" or "update CKKW"

#*********************************************************************
#
#*********************************************************************
# Phase-Space Optimization strategy (basic options)
#*********************************************************************
  0	= nhel ! using helicities importance sampling or not.
                             ! 0: sum over helicity, 1: importance sampling
  1	= sde_strategy ! default integration strategy (hep-ph/2021.00773)
                             ! 1 is old strategy (using amp square)
			     ! 2 is new strategy (using only the denominator)
#*********************************************************************
# Phase-Space Optim (advanced)
#*********************************************************************
  0	= job_strategy ! see appendix of 1507.00020 (page 26)
  0	= hard_survey ! force to have better estimate of the integral at survey for difficult mode like interference
  -1.0	= tmin_for_channel ! limit the non-singular reach of --some-- channel of integration related to T-channel diagram (value between -1 and 0), -1 is no impact
  -1	= survey_splitting ! for loop-induced control how many core are used at survey for the computation of a single iteration.
  2	= survey_nchannel_per_job ! control how many Channel are integrated inside a single job on cluster/multicore
  -1	= refine_evt_by_job ! control the maximal number of events for the first iteration of the refine (larger means less jobs)  
#*********************************************************************
# Compilation flag. 
#*********************************************************************   
  -O	= global_flag ! fortran optimization flag use for the all code.
  --fast-math	= aloha_flag ! fortran optimization flag for aloha function. Suggestions: '-ffast-math'
  -O3	= matrix_flag ! fortran optimization flag for matrix.f function. Suggestions: '-O3'
  16	= vector_size ! size of fortran arrays allocated in the multi-event API for SIMD/GPU (VECSIZE_MEMMAX)
  1	= nb_warp ! total number of warp/frontwave
			     
#*********************************************************************
# Customization (custom cuts/scale/bias/...)                         *
# list of files containing fortran function that overwrite default   *
#*********************************************************************
  	= custom_fcts ! List of files containing user hook function
#*******************************                                                 
# Parton level cuts definition *
#*******************************
  0.0	= dsqrt_shat ! minimal shat for full process
  -1	= dsqrt_shatmax ! maximum shat for full process
#                                                                    
#
#*********************************************************************
# BW cutoff (M+/-bwcutoff*Gamma) ! Define on/off-shell for "$" and decay  
#*********************************************************************
  15.0	= bwcutoff ! (M+/-bwcutoff*Gamma)
#*********************************************************************
# Standard Cuts                                                      *
#*********************************************************************
# Minimum and maximum pt's (for max, -1 means no cut)                *
#*********************************************************************
  20.0	= ptj ! minimum pt for the jets 
  -1.0	= ptjmax ! maximum pt for the jets
  {}	= pt_min_pdg ! pt cut for other particles (use pdg code). Applied on particle and anti-particle
  {}	= pt_max_pdg ! pt cut for other particles (syntax e.g. {6: 100, 25: 50}) 
#
# For display option for energy cut in the partonic center of mass frame type 'update ecut'
#
#*********************************************************************
# Maximum and minimum absolute rapidity (for max, -1 means no cut)   *
#*********************************************************************
  5.0	= etaj ! max rap for the jets 
  {}	= eta_min_pdg ! rap cut for other particles (use pdg code). Applied on particle and anti-particle
  {}	= eta_max_pdg ! rap cut for other particles (syntax e.g. {6: 2.5, 23: 5})
#*********************************************************************
# Minimum and maximum DeltaR distance                                *
#*********************************************************************
#*********************************************************************
# Minimum and maximum invariant mass for pairs                       *
#*********************************************************************
  {}	= mxx_min_pdg ! min invariant mass of a pair of particles X/X~ (e.g. {6:250})
  {'default': False}	= mxx_only_part_antipart ! if True the invariant mass is applied only 
                       ! to pairs of particle/antiparticle and not to pairs of the same pdg codes.  
#*********************************************************************
# Inclusive cuts                                                     *
#*********************************************************************
  0.0	= ptheavy ! minimum pt for at least one heavy final state
#*********************************************************************
# maximal pdg code for quark to be considered as a light jet         *
# (otherwise b cuts are applied)                                     *
#*********************************************************************
  4	= maxjetflavor ! Maximum jet pdg code
#*********************************************************************
#
#*********************************************************************
# Store info for systematics studies                                 *
# WARNING: Do not use for interference type of computation           *
#*********************************************************************
  True	= use_syst ! Enable systematics studies
#
  systematics	= systematics_program ! none, systematics [python], SysCalc [depreceted, C++]
  ['--mur=0.5,1,2', '--muf=0.5,1,2', '--pdf=errorset']	= systematics_arguments ! see: https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/Systematics#Systematicspythonmodule
#***********************************************************************
# SIMD/GPU configuration for the CUDACPP plugin
#************************************************************************
  cpp	= cudacpp_backend ! CUDACPP backend: fortran, cuda, hip, cpp, cppnone, cppsse4, cppavx2, cpp512y, cpp512z, cppauto

As an example, P1_gg_ttxttxg/G7/log.txt:

 FBRIDGE_MODE (default) =            1
 VECSIZE_USED (default) =           16
 Process in group number            1
 A PDF is used, so alpha_s(MZ) is going to be modified
 Old value of alpha_s from param_card:   0.13000000000000003     
  ****************************************
       NNPDFDriver version 1.0.3
   Grid: NNPDF23_lo_as_0130_qed_mem0.grid
  ****************************************
 New value of alpha_s from PDF nn23lo1:  0.13000000000000000     
 Define smin to   478864.00000000000     
 *****************************************************
 *               MadGraph/MadEvent                   *
 *        --------------------------------           *
 *          http://madgraph.hep.uiuc.edu             *
 *          http://madgraph.phys.ucl.ac.be           *
 *          http://madgraph.roma2.infn.it            *
 *        --------------------------------           *
 *                                                   *
 *          PARAMETER AND COUPLING VALUES            *
 *                                                   *
 *****************************************************
  External Params
  ---------------------------------
 mdl_MB =    4.7000000000000002     
 mdl_MT =    173.00000000000000     
 mdl_MTA =    1.7769999999999999     
 mdl_MZ =    91.188000000000002     
 mdl_MH =    125.00000000000000     
 aEWM1 =    132.50700000000001     
 mdl_Gf =    1.1663900000000000E-005
 aS =   0.13000000000000003     
 mdl_ymb =    4.7000000000000002     
 mdl_ymt =    173.00000000000000     
 mdl_ymtau =    1.7769999999999999     
 mdl_WT =    1.4915000000000000     
 mdl_WZ =    2.4414039999999999     
 mdl_WW =    2.0476000000000001     
 mdl_WH =    6.3823389999999999E-003
  Internal Params
  ---------------------------------
 mdl_conjg__CKM3x3 =    1.0000000000000000     
 mdl_CKM3x3 =    1.0000000000000000     
 mdl_conjg__CKM1x1 =    1.0000000000000000     
 mdl_complexi =                (0.0000000000000000,1.0000000000000000)
 mdl_MZ__exp__2 =    8315.2513440000002     
 mdl_MZ__exp__4 =    69143404.913893804     
 mdl_sqrt__2 =    1.4142135623730951     
 mdl_MH__exp__2 =    15625.000000000000     
 mdl_aEW =    7.5467711139788835E-003
 mdl_MW =    80.419002445756163     
 mdl_sqrt__aEW =    8.6872153846781555E-002
 mdl_ee =   0.30795376724436879     
 mdl_MW__exp__2 =    6467.2159543705357     
 mdl_sw2 =   0.22224648578577766     
 mdl_cw =   0.88190334743339216     
 mdl_sqrt__sw2 =   0.47143025548407230     
 mdl_sw =   0.47143025548407230     
 mdl_g1 =   0.34919219678733299     
 mdl_gw =   0.65323293034757990     
 mdl_vev =    246.21845810181637     
 mdl_vev__exp__2 =    60623.529110035903     
 mdl_lam =   0.12886910601690263     
 mdl_yb =    2.6995554250465490E-002
 mdl_yt =   0.99366614581500623     
 mdl_ytau =    1.0206617000654717E-002
 mdl_muH =    88.388347648318430     
 mdl_I1x33 =          (2.69955542504654901E-002,0.0000000000000000)
 mdl_I2x33 =               (0.99366614581500623,0.0000000000000000)
 mdl_I3x33 =               (0.99366614581500623,0.0000000000000000)
 mdl_I4x33 =          (2.69955542504654901E-002,0.0000000000000000)
 mdl_ee__exp__2 =    9.4835522759998875E-002
 mdl_sw__exp__2 =   0.22224648578577769     
 mdl_cw__exp__2 =   0.77775351421422245     
  Internal Params evaluated point by point
  ----------------------------------------
  
 mdl_sqrt__aS =   0.36055512754639896     
 mdl_G__exp__2 =    1.6336281798666927     
  Couplings of sm
  ---------------------------------
  
        GC_10 =  -0.12781E+01   0.00000E+00
        GC_11 =   0.00000E+00   0.12781E+01
        GC_12 =   0.00000E+00   0.16336E+01
 Collider parameters:
 --------------------
 Running at P P   machine @    13000.000000000000       GeV
 PDF set = nn23lo1
 alpha_s(Mz)= 0.1300 running at 2 loops.
 alpha_s(Mz)= 0.1300 running at 2 loops.
 Renormalization scale set on event-by-event basis
 Factorization   scale set on event-by-event basis
 getting user params
Enter number of events and max and min iterations: 
 Number of events and iterations         2000           8           3
Enter desired fractional accuracy: 
 Desired fractional accuracy:    1.0000000000000000E-002
Enter 0 for fixed, 2 for adjustable grid: 
Suppress amplitude (0 no, 1 yes)? 
 Using suppressed amplitude.
Exact helicity sum (0 yes, n = number/event)? 
 Explicitly summing over helicities
Enter Configuration Number: 
Running Configuration Number:    7
 Not subdividing B.W.
 Attempting mappinvarients           1           7
 Determine nb_t
 T-channel found:            0
 Completed mapping           7
 about to integrate           13        2000           8           3          13           1
 Using non-zero grid deformation.
 13 dimensions   2000 events 13 invarients  8 iterations  1 config(s),  (0.99)
 Using h-tuple random number sequence.
 Error opening grid
 Using Uniform Grid!          28
 Using uniform alpha   1.0000000000000000     
 Grid defined OK
 Masses: 0.000E+00 0.000E+00 0.173E+03 0.173E+03 0.173E+03 0.173E+03 0.000E+00
 Set CM energy to      13000.00
 Mapping Graph           7  to config           7
 Determine nb_t
 T-channel found:            0
Setting grid   1    0.70838E-03   1
Setting grid   2    0.70838E-03   1
Setting grid   3    0.70838E-03   1
 Transforming s_hat 1/s           12   2.9996686390532548E-003   478864.00000000000        168999999.99999997     
Using random seed offsets     7 :      1
  with seed                   24
 Ranmar initialization seeds       31065        9398
  Particle       3       4       5       6       7
      Et >     0.0     0.0     0.0     0.0    20.0
       E >     0.0     0.0     0.0     0.0     0.0
     Eta <    -1.0    -1.0    -1.0    -1.0     5.0
   xqcut:      0.0     0.0     0.0     0.0     0.0
d R # 3  >    -0.0     0.0     0.0     0.0     0.0
d R # 4  >    -0.0    -0.0     0.0     0.0     0.0
d R # 5  >    -0.0    -0.0    -0.0     0.0     0.0
d R # 6  >    -0.0    -0.0    -0.0    -0.0     0.0
s min # 3>     0.0119716.0119716.0119716.0     0.0
s min # 4>     0.0     0.0119716.0119716.0     0.0
s min # 5>     0.0     0.0     0.0119716.0     0.0
s min # 6>     0.0     0.0     0.0     0.0     0.0
xqcutij # 3>     0.0     0.0     0.0     0.0     0.0
xqcutij # 4>     0.0     0.0     0.0     0.0     0.0
xqcutij # 5>     0.0     0.0     0.0     0.0     0.0
xqcutij # 6>     0.0     0.0     0.0     0.0     0.0
 NGOODHEL =         128
 NCOMB =         128
 MULTI_CHANNEL = TRUE
 CHANNEL_ID =           8
 Error: failed to reduce to color indices:            1           1
ls status:
input_app.txt
run1_app.log

Ping: @oliviermattelaer

[roiser]

FYI, just tried with 3.6.5 and can still produce this error

[oliviermattelaer]

Surprisingly, this does not seem to be problematic if run without cudacpp plugin...
So maybe this indicates a missmatch on the color between the two codes...