NOTE: Python 3.9.3 contains an unintentional ABI incompatibility on 32-bit systems

The memory layout of PyThreadState was unintentionally changed in the recent 3.9.3 bugfix release. This leads to crashes on 32-bit systems when importing binary extensions compiled for Python 3.9.0 - 3.9.2. This is a regression.

We will be releasing a hotfix 3.9.4 around 24 hours from now to address this issue and restore ABI compatibility with C extensions built for Python 3.9.0 - 3.9.2.

Details in Issue 43710: Access violations in C extension modules on Python 3.9.3 - Python tracker.