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uv sync fails: PyO3 does not yet support Python 3.14 #2

@starrust

Description

@starrust

🐛 Bug Description

Following the Quickstart guide — step 2:

uv sync

The dependency installation fails with the following error:

error: the configured Python interpreter version (3.14) is newer than PyO3's maximum supported version (3.13)

According to the build logs, the failure occurs when building pydantic-core==2.33.2, because PyO3 (v0.24.1) currently does not support Python 3.14.


⚙️ Steps to Reproduce

  1. Use a Python 3.14 environment.
  2. Run:
    uv sync
  3. Observe the failure during pydantic-core build.

✅ Workaround

Before running uv sync, install and pin Python 3.13:

uv python install 3.13
uv python pin 3.13
uv sync

This resolves the issue and installs all dependencies successfully.


💡 Suggestion

Please update the Quickstart or Setup instructions to explicitly mention that Python 3.13 is required for now, as PyO3 (used by pydantic-core) does not yet support Python 3.14.
This will help others avoid the same installation error.


🧩 Additional Context

  • Failing package: pydantic-core==2.33.2
  • Rust library: PyO3 v0.24.1
  • PyO3’s max supported Python version: 3.13
  • Build tool: uv
  • Affected step: Quickstart → Step 2 (“Install dependencies”)

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