Re: Why these (apparently harmless) error messages?
It is harmless. win32com, from pywin32, is conditionally imported by distutils.msvccompiler which is standard lib. PyInstaller has a special hook file telling it how to load win32com but it doesn’t cover the case where it is not installed (it probably should) so it trips the ImportError you’re seeing. PyInstaller can’t include win32com as you don’t have it but unless you genuinely want to use the msvc compiler from a PyInstaller bundle this shouldn’t do anything. If you really don’t like it, passing --exclude win32com prevents the above.