I search the forum but couldn’t find the answer.
Why is this happend?
Error:
Inputs:

import Autodesk #Loads the Autodesk namespace
import Autodesk.Revit.DB as RDB #Loading Revit's API UI classes module kan nu worden aangeroepen met RDB.xxxx
#from Autodesk.Revit.DB import * #Loading Revit's API UI classes
import Autodesk.Revit.UI as RUI # Loading Revit's API UI classes als RUI.xxxx
#from Autodesk.Revit.UI import * #Loading Revit's API UI classes
def GetName(ele):
elename = None
try:
elename = ele.Name
except:
elename = RDB.Element.Name.__get__(ele)
return elename
#einde code omrekenen revit feet naar huidig ingestele document units
#categoriëen ophalen
cat_list = [RDB.BuiltInCategory.OST_PipeCurves, RDB.BuiltInCategory.OST_PipeFitting]
typed_list = MGen.List[RDB.BuiltInCategory](cat_list)
filter = RDB.ElementMulticategoryFilter(typed_list)
elementen = RDB.FilteredElementCollector(doc).WherePasses(filter).WhereElementIsNotElementType().ToElements()
#Alle pipes en fittings ophalen
pipe_elem = []
for nw in elementen:
p_name = GetName(nw)
if p_name.Contains("Bochtstraal") or p_name.Contains("Alupex"):
pipe_elem.append(nw)
#Pipe fittingen ophalen
pipe_fitting = []
for pf in pipe_elem:
pf_name = GetName(pf)
if pf_name.Contains("Bochtstraal"):
pipe_fitting.append(pf)
#geconnecte pipe ophalen
refs = []
for x in pipe_fitting:
connset = x.MEPModel.ConnectorManager.Connectors
conn_pipes = []
for c in connset:
if c.IsConnected:
for lc in c.AllRefs:
conn_pipes.append(lc.Owner)
refs.append(conn_pipes)
#section van geconnecte buis ophalen
p_section = []
for r in refs:
p_section.append([]) #lege lijst maken voor behoudt structuur
for i in r:
section = i.get_Parameter(RDB.BuiltInParameter.RBS_SECTION).AsValueString()
p_section[-1].append(section) #-1 zorgt ervoor dat lijst in structuur blijft.
#Unique items eruit halen
ukeys= p_section
listOfList = [ukeys]
ukeys1 = [item[0] for item in ukeys]
ukeys2 = []
for u in ukeys1:
ukeys2.append(int(u))
#Start Transaction
TransactionManager.Instance.EnsureInTransaction(doc)
n_section = []
for pf in pipe_fitting:
n_section.append(pf.LookupParameter("Section").Set(ukeys2))
TransactionManager.Instance.TransactionTaskDone()
OUT= n_section