C# Excel interop - how to test if interop object is still working and performing a task?

Question

I am looping through a directory of several hundered excel files and trying to refresh the excel files one at a time. I keep getting this error which indicates that the refr

Answer 1

I found an answer to my problem. I needed to implement IMessageFilter RetryRejectedCall. For a C# and VB.NET code sample of using IMessageFilter::RetryRejectedCall, see this blog post (wayback machine archived link).

If you don't register a MessageFilter yourself (by calling CoRegisterMessageFilter), you will get default behavior which will be to fail the call if it gets rejected.  .Net converts the failure HRESULT to an exception.  To deal with the possibility of the server being busy when you try to call, you need to implement IMessageFilter::RetryRejectedCall in your client code and also register the message filter.  In most cases, you will just need to wait for a few seconds and then retry the call--generally that will be sufficient time to enable Word to finish whatever it is doing so it can handle your call.