There are many programs out there, including Django, that "carefully import" a module by doing: try: import simplejson except ImportError: import whatever_instead as simplejson # or whatever This is problematic because sometimes an `ImportError` is raised not because the module is missing, but because there's some error in the module, or because the module raises an `ImportError` itself. Then the exception gets totally swallowed, resulting in delightful debugging sessions. What do you think about having an exception `ModuleNotFoundError` which is a subclass of `ImportError`? Then people could `except ModuleNotFoundError` and be sure that it was caused by a module not existing. This will be a much better way of "carefully importing" a module. Would this be backwards-compatible? Ram.