I took a year off from XNA to work on other stuff. I recently found some time to open up some of my projects. The project I am working on was started in XNA 1.0. I have followed all the guidelines for moving it up to 2.0. I am still getting an exception. I cannot understand why. This is the exception I am getting

System.InvalidOperationException was unhandled
  Message="The operation was aborted. You may not modify a resource that has been set on a device, or after it has been used within a tiling bracket."
 

It happens at an IndexBuffer.setdata call. The documentation briefly mentions this, but I am not clear on why this exception gets thrown in 2.0 but not 1.0.  Can any one help me with this? Thanks!

Here is the quote from the XNA documentation under IndexBuffer.SetData<>.

Remarks

MarkF:

Can anyone explain what a resource being "set" on a graphics device means.

For an index Buffer, it means that  GraphicsDevice.Indices has the value of that index buffer

For vertex Buffers, it means GraphicsDevice.Vertices[.SetSource() was recently used with that vertex buffer as a parameter, maybe for drawing something. Even though it may not be used at this moment, it is still prepared on the device for usage, so you cannot modify it.

Just make sure the buffers are no longer set on the device:

 GraphicsDevice.Indices = null;

GraphicsDevice.Vertices[0].SetSource(null, 0, 0);