topic Re: [Revit 2024] In Python node in Dynamo doc.LoadFamily does not accept loadoptions anymore. in Revit API Forum

[Revit 2024] In Python node in Dynamo doc.LoadFamily does not accept loadoptions anymore.

j.podlaha — Mon, 29 May 2023 21:38:25 GMT

When I call `familyDoc.LoadFamily(doc, FamilyLoadOptions())` in Revit 2024 I get following error:

TypeError: interface takes exactly one
argument [' File "«string›", line 97, in
<module>\n']

This code used to work, but the method seems to no longer accept the second argument, which doesn't seems correct. Is this my bug or a bug in Revit 2024 Python API or maybe a API change, or am I missing something else??

----

I originally posted the question with more context in dynamobim forums:

https://forum.dynamobim.com/t/how-do-i-define-a-family-parameter-in-revitapi-2024-using-python-block-in-designscript/89816/4?u=jakub.podlaha

Entire source code:

import sys import clr clr.AddReference("RevitServices") from RevitServices.Persistence import DocumentManager from RevitServices.Transactions import TransactionManager clr.AddReference("RevitAPI") import Autodesk from Autodesk.Revit.DB import * ## Input parameters familyName = IN[0] family = UnwrapElement(IN[1]) ## Test if family already contains the parameter def familyHasParameter(family, parameterName): currentParams = family.FamilyManager.GetParameters() for k in range(len(currentParams)): if currentParams[k].Definition.Name == parameterName: return True return False ## Get Family document from family instance def getFamilyDoc(fam, doc): if isinstance(fam, Autodesk.Revit.DB.FamilyInstance): return (Document.EditFamily(doc, fam.Symbol.Family)) else: if fam.IsInPlace == False: return (Document.EditFamily(doc, fam)) ## Implementation of family load options - always override existing family class FamilyLoadOptions(IFamilyLoadOptions): def OnFamilyFound(self, familyInUse, overwriteParameterValues): overwriteParameterValues = True return True def OnSharedFamilyFound(self, sharedFamily, familyInUse, source, overwriteParameterValues): source = FamilySource.Family overwriteParameterValues = True return True ########################################################### TransactionManager.Instance.TransactionTaskDone() TransactionManager.Instance.ForceCloseTransaction() doc = DocumentManager.Instance.CurrentDBDocument print("-- Editing family: " + familyName) familyDoc = getFamilyDoc(family, doc) TransactionManager.Instance.EnsureInTransaction(doc) trans = Transaction(familyDoc, "Edit family params") trans.Start() parameterName = "TEST" groupTypeId = Autodesk.Revit.DB.GroupTypeId.Data specTypeId = Autodesk.Revit.DB.SpecTypeId.Current isInstance = True if familyHasParameter(familyDoc, parameterName): print(("-- Parameter already exists on family: " + parameterName)) else: print(("-- Adding parameter to family: " + parameterName)) familyDoc.FamilyManager.AddParameter(parameterName, groupTypeId, specTypeId, isInstance) trans.Commit() trans.Dispose() TransactionManager.Instance.TransactionTaskDone() TransactionManager.Instance.ForceCloseTransaction() print("-- Saving family to project") familyDoc.LoadFamily(doc, FamilyLoadOptions()) TransactionManager.Instance.TransactionTaskDone() TransactionManager.Instance.ForceCloseTransaction()

Re: [Revit 2024] In Python node in Dynamo doc.LoadFamily does not accept loadoptions anymore.

architect.bim — Tue, 30 May 2023 05:18:33 GMT

Hi!

This is definetly CPython3 problem. I've made a short test. And LoadFamily method accepts load options just fine if you use IronPython2 in Dynamo instead:

f_doc = doc.EditFamily(family) TransactionManager.Instance.EnsureInTransaction(f_doc) f_doc.FamilyManager.NewType("Test") TransactionManager.Instance.TransactionTaskDone() f_doc.LoadFamily(doc, FamilyLoadOptions())

Worked fine in Revit 2024. But when I switched to CPython3 the same error happened.

Re: [Revit 2024] In Python node in Dynamo doc.LoadFamily does not accept loadoptions anymore.

j.podlaha — Mon, 05 Jun 2023 18:32:27 GMT

Hey, thanks a lot for helping to figure this out. How should I handle this issue now? Is there a bugtracker to report this to? Switching back to IronPython2 currently doesn't work for me (I struggle to do the switch in current Revit).

Re: [Revit 2024] In Python node in Dynamo doc.LoadFamily does not accept loadoptions anymore.

architect.bim — Tue, 06 Jun 2023 09:03:35 GMT

Hi!

I think the best way to report the bug is in their repository on Github. But first, read this article, maybe this bug is already listed there.

As for using IronPython2 - it works fine. If you write more details about what you're having trouble with, maybe I can help. In my opinion it's a better option than waiting for Dynamo CPython3 developers to fix all the bugs.

Re: [Revit 2024] In Python node in Dynamo doc.LoadFamily does not accept loadoptions anymore.

jacob.small — Fri, 09 Jun 2023 12:17:11 GMT

I've shared this a few times in the Dynamo forum, but apparently not to a wide enough audience, so I'll post this here as well.

This isn't an issue with CPython, but more likely with Python 3 entirely as IronPython3 fails similarly. As such reporting to the Dynamo GitHub wont' help much - you'll have to go to the Python one instead. The reason this fails now is that classes required a namespace to pass to the .net environment cleanly. If you provide a namespace things should work without issue for the first run.

However namespaces cannot be duplicated in the same kernal, and as the class with it's namespace has been passed once already it either needs to be disposed after run (haven't tested this as it isn't something which I have needed in my work of late) or a unique namespace needs to be generated for each run (works without issue for a few hundred runs while developing code anyway).

A non-Revit centered version of the problem and the same solution can be found here: https://stackoverflow.com/a/50462691

Re: [Revit 2024] In Python node in Dynamo doc.LoadFamily does not accept loadoptions anymore.

b_neterebskiiFSAA9 — Tue, 25 Mar 2025 14:35:52 GMT

I find out that it is possible to handle this problem using new Namespace everytime. E.g. with uuid function. Here is the example:

import uuid class WarningFailureMessageClass(IFailuresPreprocessor): __namespace__ = str(uuid.uuid4()) def PreprocessFailures(self, failuresAccessor): fail_acc_list = failuresAccessor.GetFailureMessages() for failure in fail_acc_list: severity = failure.GetSeverity() if severity == FailureSeverity.Warning: failuresAccessor.DeleteWarning(failure) return FailureProcessingResult.Continue def suppress_warnings(transaction): fail_opt = transaction.GetFailureHandlingOptions() preprocessor = WarningFailureMessageClass() fail_opt.SetFailuresPreprocessor(preprocessor) transaction.SetFailureHandlingOptions(fail_opt)

Re: [Revit 2024] In Python node in Dynamo doc.LoadFamily does not accept loadoptions anymore.

e.j.nap — Tue, 08 Jul 2025 08:38:32 GMT

Works like a charm! I would never have come up with this solution.

It seems a bit strange though. It deliberatly obfuscates the namespace for the .NET interpreter. Could this cause some sort of degredation of the .NET interpreter functionality in the long run, or are these new namespaces not stored after a run where this class is instantiated?

Re: [Revit 2024] In Python node in Dynamo doc.LoadFamily does not accept loadoptions anymore.

LoganAC34 — Tue, 05 Aug 2025 14:00:56 GMT

@b_neterebskiiFSAA9 wrote:
I find out that it is possible to handle this problem using new Namespace everytime. E.g. with uuid function. Here is the example:

Unless i'm doing it wrong, using a uuid for the namespace always crashes Revit for me after 20-30 iterations. I've tried moving the 'family_load_options = FamilyLoadOptions()' line outside of the loop and it does the same thing. I also tried setting a static non-uuid string for the name space like the stackoverflow post and still the same thing. Nothing works for me for long. It's not the other parts of my code either, because if i run it without trying to load the family back into the project, everything works fine.

class FamilyLoadOptions(IFamilyLoadOptions): """A Class implementation for loading families""" __namespace__ = str(uuid.uuid4()) def OnFamilyFound(self, familyInUse, overwriteParameterValues): """Defines behavior when a family is found in the model.""" overwriteParameterValues = True return True def OnSharedFamilyFound(self, sharedFamily, familyInUse, source, overwriteParameterValues): """Defines behavior when a shared family is found in the model.""" source = FamilySource.Project # source = FamilySource.Family overwriteParameterValues = True return True ## This is in a 'for' loop family_load_options = FamilyLoadOptions() famDoc.LoadFamily(doc, family_load_options)

Re: [Revit 2024] In Python node in Dynamo doc.LoadFamily does not accept loadoptions anymore.

Trinh_TH — Tue, 28 Apr 2026 09:23:19 GMT

No need for the "IFamilyLoadOptions"

Just use:
success = doc.LoadFamily(path)

Re: [Revit 2024] In Python node in Dynamo doc.LoadFamily does not accept loadoptions anymore.

jacob.small — Tue, 28 Apr 2026 10:00:15 GMT

Per the documentation, the call doc.LoadFamily(path) will only work if there isn't a family with the same name in the document. If there is a matching family you'll get an warning.