This version solidifies support for Python 3.14 and free-threaded Python 3.14t. A number of PyO3 APIs have been renamed to reflect the fact the GIL is no longer a universal feature of all Python implementations. For example:

• Python::with_gil is now known as Python::attach
• Python::allow_threads is now known as Python::detach
• pyo3::prepare_freethreaded_python is now known as Python::initialize()

The minimum supported Rust version has been increased to Rust 1.74.

An optional dependency on the bytes crate has been added to allow support for converting bytes::Bytes to / from Python.

The PyObject type alias for Py<PyAny> has also been deprecated; the Py and Bound smart pointers have been the primary interface for all Python-facing types since PyO3 0.21 and the PyObject type alias had been a frequent source of confusion.

There are also many other incremental improvements, bug fixes and smaller features.

Please consult the for help upgrading.