problem uploading ZIP file tp PyPI

[John Machin]

Sorry in advance if this is not the correct forum ...

I'm trying to upload what appears to be a perfectly OK zip file as a
"source" file type to PyPI, and am getting this response:

Error...
There's been a problem with your request
exceptions.ValueError: invalid distribution file

I have managed to upload a Windows installer, and downloaded it again
[but the download count is still stuck on zero].

Any clues?