Thanks for your report, Rich.  configparser is one of the oldest libraries in the standard library.  Its behavior might sometimes not be intuitive to newcomers but is burdened by years of backwards compatibility.  Changing the behavior now to raise a type error on an open file passed to read would inevitably cause some program in the wild to break.  Given this constraint, there's not much we can do besides documentation.  If you have suggestions how we could improve it, let me know here.