I recently discovered that import win32ui was broken in Python 3.9. This is described in https://github.com/mhammond/pywin32/issues/1593.
I upgraded pywin32 from the build I had (288) to the latest build (301) and that made the import problem go away. But today I ran a pygame application that was packaged as an .exe with pyinstaller before I upgraded pywin32. On startup it issued the popup The procedure entry point PyWinObject_AsWriteBuffer [C++ name mangling] could not be located in the dynamic link library C::\Windows\SYSTEM32\pythoncom39.dll. I dismissed this message and the application ran as usual, which was a relief. Now this was clearly caused by the new build of the DLL not containing an entry point that was previously there. From the Python docs I see that this entry point is associated with the C API function PyObject_AsWriteBuffer which supports the deprecated old Python buffer protocol (https://docs.python.org/3/c-api/objbuffer.html). So I upgraded pygame from 1.9.6 to 2.0.1 and repackaged the application. This time, during the pyinstaller run, I got the same popup from pyinstaller that previously appeared when starting the application. After dismissing this the packaging proceeded as normal. And the packaged .exe does not now issue the warning on startup. This is relatively harmless, and certainly not a showstopper, but it does appear that pygame is expecting there to be an entry point in pythoncom39.dll that is no longer there. I suppose I could get the build 288 version of the DLL and override the packaging to include it instead of the latest version, but that strikes me as the tail wagging the dog. -- Paul Keating Soustons, Nouvelle Aquitaine, France
