RhinoCAM FAQs > System Errors > How to: Fix the "No Class Derived" Error

If the RhinoCAM plugin fails to load and errors out with No class derived from CRhinoPlugin in plugin file, perform the following steps:

1.Close Rhino.

2.Download the .zip file from the following link: click here. Download it to your downloads folder.

3.Go to your downloads folder, right click on the file and then click Extract All.

4.After you extract the folder, you will see a file with .reg extension. Select this file, right mouse button click and choose Merge. Click Yes when prompted by windows user account control.

5.Then select Yes and OK.

6.Now open Rhino and this should load your RhinoCAM plug-in.

7.If the plug-in still fails to load and displays the above error, close Rhino.

8.Open your Registry editor by typing regedit into the Windows search field.

Windows 8 & 8.1: From the windows charms bar on the right in the search box type regedit
Windows 10: type regedit under Search the web and Windows in your task bar.

9.From the left panel navigate to HKEY_CURRENT_USER -> SOFTWARE -> Microsoft -> Windows NT -> CurrentVersion -> AppCompatFlags -> Layers

10.On the right panel locate the line containing:
C:\Program Files\Rhinoceros x (64-bit)\System\Rhino.exe and Data set to $ IgnoreFreeLibrary<RhinoCAM For Rhinox.0.rhp>

11.Delete this line and close registry editor.

12.Open Rhino and make sure the RhinoCAM plug-in loads.

Several other Rhino plug-ins have had this error. Click here for more information.