What causes IndexError: tuple index out of range in py2exe

Question

I've just installed Python 3.8.5 and py2exe 0.9.2.2. I have a setup.py that works with py2exe 0.6.9 on Python 2.7. When I run setup.py py2exe (the actual command line is py setupexe.py py2exe) with the new version I get:

    Traceback (most recent call last):
      File "setupexe.py", line 4, in <module>
        setup(name='md2html',
      File "C:\Program Files\Python38\lib\distutils\core.py", line 148, in setup
        dist.run_commands()
      File "C:\Program Files\Python38\lib\distutils\dist.py", line 966, in run_commands
        self.run_command(cmd)
      File "C:\Program Files\Python38\lib\distutils\dist.py", line 985, in run_command
        cmd_obj.run()
      File "C:\Users\Gary\AppData\Roaming\Python\Python38\site-packages\py2exe\distutils_buildexe.py", line 188, in run
        self._run()
      File "C:\Users\Gary\AppData\Roaming\Python\Python38\site-packages\py2exe\distutils_buildexe.py", line 267, in _run
        builder.analyze()
      File "C:\Users\Gary\AppData\Roaming\Python\Python38\site-packages\py2exe\runtime.py", line 160, in analyze
        self.mf.import_hook(modname)
      File "C:\Users\Gary\AppData\Roaming\Python\Python38\site-packages\py2exe\mf3.py", line 120, in import_hook
        module = self._gcd_import(name)
      File "C:\Users\Gary\AppData\Roaming\Python\Python38\site-packages\py2exe\mf3.py", line 274, in _gcd_import
        return self._find_and_load(name)
      File "C:\Users\Gary\AppData\Roaming\Python\Python38\site-packages\py2exe\mf3.py", line 357, in _find_and_load
        self._scan_code(module.__code__, module)
      File "C:\Users\Gary\AppData\Roaming\Python\Python38\site-packages\py2exe\mf3.py", line 388, in _scan_code
        for what, args in self._scan_opcodes(code):
      File "C:\Users\Gary\AppData\Roaming\Python\Python38\site-packages\py2exe\mf3.py", line 417, in _scan_opcodes
        yield "store", (names[oparg],)
    IndexError: tuple index out of range

The setup.py:

from distutils.core import setup
import py2exe
from md2html import __VERSION__
setup(name='md2html',
      version=__VERSION__,
      author='xxxxx',
      author_email='xxxxx',
      description='Convert Markdown to HTML',
      requires=['markdown(>=2.6.6)'],
      console=['md2html.py'],
      options={"py2exe":{
          "excludes": [
              'pyreadline', 'difflib', 'doctest', 'optparse', 'pickle', 'calendar', 'email', 'ftplib', 'httplib', 'rfc822', 'socket', 'select', 'ssl', '_ssl']  # Exclude standard library
               }}
)

As I said, this worked before. My next step would be to run it in pdb, but before I jump into unfamiliar code, I thought I'd ask. Running on Windows 10. Thanks. Update: This question produces a similar error. The answer is that py2exe doesn't work with versions after Python 3.4. Disappointing! It suggests pyinstaller, which I will investigate. I really hope there's a way to make py2exe work.