Incompatible signatures when spawning thread with ThreadPool.QueueUserWorkitem

Question

The error is:

Method 'Private Sub ProcessToolWork()' does not have a signature compatible with delegate 'Delegate Sub WaitCallback(state As Object)'.

What's the deal here? I've never experienced this error spawning a thread in this fashion.

Here are my routine definitions:

Public Sub ProcessWork()
      ThreadPool.QueueUserWorkItem(AddressOf ProcessToolWork)
End Sub

Private Sub ProcessToolWork()

End Sub

See anything wrong?

I've also tried making a new WaitCallback for this item like so:

ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf ProcessToolWork))

Answer 1

WaitCallback takes a state argument (of type Object). Even if you ignore it, you have to put it in your method signature:

Private Sub ProcessToolWork(ByVal ignored As Object)

End Sub