Yes, I also got the error 'link.exe' failed with exit code 1104. The files foo.pyx and foo.c were located on a share. The path was rather long. Or maybe the spaces in the path caused trouble. When I copied those files to folder C:\temp and I ran the command 'cythonize -a -i foo.pyx' there, the error did not occur again and the build finished without problems: "Finished generating code" and "copying build\lib.win-amd64-3.8\foo.cp38-win_amd64.pyd".