When AutoCAD 2027 was first released with .NET 10 support, many developers encountered a critical regression: drag-and-drop operations from custom palettes to the drawing area would crash with an InvalidCastException.
System.InvalidCastException: Unable to cast COM object of type 'System.__ComObject'
to interface type 'System.Windows.Forms.IDataObject'.
QueryInterface call failed with E_NOINTERFACE (0x80004002).What Caused It?
This was a compatibility issue introduced by breaking changes in .NET 9 (which carried over into .NET 10):
- PR dotnet/winforms#10759 changed how
Control.DoDragDrop()wraps data objects. System.Windows.Forms.IDataObjectlost its COM visibility in .NET 5 (PR #3388).- AutoCAD’s internal drag-and-drop handler was no longer able to cast the COM object.
Affected Versions
- AutoCAD 2024–2026 (.NET Framework 4.8 / .NET 8) — Worked fine
- AutoCAD 2027 RTM (.NET 10) — Broken
The Fix
Good news! Autodesk has resolved this issue in AutoCAD 2027 Update 1.
Download the Fix
You can download the update directly from the Autodesk Portal:
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