21CTO

Dec 20, 2025 · Fundamentals

What’s New in Python 3.15 Alpha 3? Profiling, UTF‑8 Default, and Error Message Improvements

Python 3.15.0 alpha 3, the third of seven planned pre‑release versions, introduces a high‑frequency low‑overhead statistical profiler, makes UTF‑8 the default source encoding, adds a new C‑API for byte objects, and delivers clearer error messages, all while remaining a test‑only build.