You didn't tell what operating system you're running. If you're on a Mac, this should provide an answer:
One place I see this message on a regular basis is when I try to open a file by double clicking it in an OS folder, but I left a dialog box open in InDesign. When get back to InDesign and close the dialog box, this resolves itself.
If you are unsure if that is your situation, try shutting down InDesign and reopening it and then try reopening the file.
what exactly is this "request" InDesign cannot handle?
What are you trying to do when this message comes up?
( ACP )