How to upgrade/update pyo3?

[AxelNennker]

Hi,
I get the error message that my Python3 is to new for pyo3. There is a new version.

Running maturin pep517 build-wheel -i /Users/<redacted>/venv/bin/python3 --compatibility off
...
error: the configured Python interpreter version (3.13) is newer than PyO3's maximum supported version (3.12)
= help: please check if an updated version of PyO3 is available. Current version: 0.21.1

Latest version is currently 0.27.1

I updated rust, python3, pip, maturin and installed py03-pack, but the error message stays the same.
I am on macos Tahoe and pip tells me to use brew.

cargo add pyo3 does not work because there is no Cargo.toml

I guess I must tell maturin to use the newer pyo3, but how do I do that?

$ maturin --version
maturin 1.10.1

$ python3 --version
Python 3.13.5

$ cargo --version
cargo 1.91.1 (ea2d97820 2025-10-10)

$ pip3 list
Package   Version
--------- -------
pip       25.3
pyo3-pack 0.6.1

How do I update from pyos 0.21.1 to 0.27.1, which hopefully supports python 3.13.

Thank you

Axel

ps: Feature request:
Get latest release version from crates.io/crates/pyo3 and tell user in error message how to update to that

[LilyFirefly]

Hi @AxelNennker!

There are several possible project layouts possible when using maturin. Most of these have a Cargo.toml at the top level of the project, but you may be using the Alternate Python source directory (src layout) or similar where the Cargo.toml file is in a subdirectory.

Once you've found the Cargo.toml you can update it to use a more modern PyO3. I recommend following the migration guide, starting with 0.21 to 0.22.

[davidhewitt]

As well as @LilyFirefly's solution above I think there is a possible alternative here, which is that the user is installing a package which is itself built using PyO3.

In this case the user will need to identify which package has failed to build, and upgrade that package.

[AxelNennker]

Thanks for the answers.

There is not Cargo.toml in the source code that I got from a partner.

$ find . -name Cargo.toml

I try to install requiremnts.txt and bummer with the error that python 3.13 is not supported by this pyo3 version.

I solved my problem by putting everything into docker with python 3.12

I asked that partner to update to the latest pyo3

Thanks again.