I mistakenly added fields to the middle of PyDateTimeAPI and PyFrameObject between the 7.3.5 release and the 7.3.6 release. This broke the promise of ABI compatibility between all the 7.3.x releases for the python 3.7 version. Python 3.8 had a different problem connected with the values of INCLUDEPY and LIBDIR in _sysconfidata that led to cases of inability to build c-extension modules. I have released PyPy 7.3.7 to fix these issues. I have also extended the weekly testing in https://github.com/pypy/binary-testing <https://github.com/pypy/binary-testing> which hopefully will catch ABI breakage before a release. Please do not use the 7.3.6 releases. Sorry for the trouble, Matti