Unable to insert rows into a M-N relationship table via arcpy script

[ArshiyaNisa]

We are trying to insert rows into a many to many relationship table via arcpy script. Attempting to write new rows with insertcursor causes an error. Manually adding data to relationship table works fine.

RuntimeError: Message: Unable to complete operation.
Details: Internal error during object insert. Invalid foreign key value

We have checked the following things-

1. GlobalIDs existing in both the parent tables.
2. GlobalIDs are valid.

Below is the sample snippet of code-

aprx = arcpy.mp.ArcGISProject("CURRENT")
m = aprx.activeMap

mc_guid = '{0196282F-17E7-4A29-A2E4-0B381C407A30}'
ls_guid = '{5FB63569-5792-42H7-AAA9-3E7A912F3226}'
lsmc_rel = m.listTables("R_Table1_Table2)[0]

with arcpy.da.InsertCursor(lsmc_rel, ['T1_GlobalID', 'T2_GlobalID']) as cursor:
cursor.insertRow((mc_guid, ls_guid))

Version details- 

Enterprise Version- 11.5

ArcGIS Pro- 3.5

[ArshiyaNisa · Accepted solution]

This error was found and there's no proper solution for it yet.

160271: Invalid foreign key value | ArcGIS Pro documentation

We've tried ArcGIS API for Python instead of Arcpy for editing features and it worked-

import arcpy

from arcgis.gis import GIS

import arcgis

from arcgis.features import FeatureLayer

aprx = arcpy.mp.ArcGISProject("CURRENT")

m = aprx.activeMap

gis = GIS("home")

# Relationship table from the map

rel_tbl = m.listTables("R_Table1_Table2")[0]

cp = rel_tbl.connectionProperties

service_url = arcpy.Describe(rel_tbl).catalogPath

version_name = "Username.test_Version"  #Change to your version name

fl = FeatureLayer(service_url, gis)

result = fl.edit_features(

    adds=[

        {

            "attributes": {

                "T1_GlobalID": "{0196282F-17E7-4A29-A2E4-0B381C407A30}",

                "T2_GlobalID": "{5FB63629-5792-42A5-AAA9-3E7A912F3226}"

            }

        }

    ],

    gdb_version= version_name

)

print(result)