How do I make add-in using out from opened document?

XARMA — Thu, 29 May 2025 01:30:35 GMT

I have saw some add-in that can be used without opening rvt file.

I face some error message, If I execute my dll file eventhough any simple codes it is.

Syetem.NullReferenceException: Object reference not set to an instance of an object at A.Command.Execute(ExternalCommandData commandData, String& message, ElementSet elements) at ...

Re: How do I make add-in using out from opened document?

naveen.kumar.t — Sun, 01 Jun 2025 11:11:57 GMT

Hi @XARMA ,

If you want logic that runs when Revit starts (before any file is opened), implement IExternalApplication and use OnStartup:

public class MyApp : IExternalApplication { public Result OnStartup(UIControlledApplication application) { // Add UI or run logic here return Result.Succeeded; } public Result OnShutdown(UIControlledApplication application) { return Result.Succeeded; } }

Also, please take a look at the links

https://help.autodesk.com/view/RVT/2024/ENU/?guid=Revit_API_Revit_API_Developers_Guide_Introduction_Add_In_Integration_External_Application_html

If this doesn't help, Could you please explain your issue in more detail?

topic Re: How do I make add-in using out from opened document? in Revit API Forum

How do I make add-in using out from opened document?

Re: How do I make add-in using out from opened document?