FastAPI 0.143.2 is a small maintenance release, but it carries one behavioural fix that matters for anyone serving a single-page frontend from the same process as their API. The rest of the changelog is routine housekeeping: translation refreshes and dependency bumps.
The headline change addresses blocking frontend fallback file checks, landed by @tiangolo in PR #16503. In apps that mount static files and fall back to an index.html when a path is not found, those checks could run in a blocking manner on the event loop. This patch tightens that path so the fallback resolution no longer stalls async request handling.
- Fix: blocking frontend fallback file checks (PR #16503, by @tiangolo)
- Translations: update-outdated refreshes for
zh-hant,ja,zh,hi,es,fr,ko,de,uk,tr,ptandru, each viapr-submit[bot] - Internal: bump
pydantic-ai-slimfrom2.49.0to2.53.0(PR #16487) - Internal: bump
werkzeugfrom3.1.6to3.1.9(PR #16464)
The block of translation updates covers twelve locales, so non-English docs sites pick up corrected, previously outdated strings without maintainers editing each page by hand.
Why it matters: if you run StaticFiles with an SPA fallback alongside async endpoints, you may have seen latency spikes or warnings when many unmatched routes hit disk. Upgrading with pip install --upgrade fastapi pulls in the non-blocking behaviour, and there are no API changes or migration steps. The dependency bumps are confined to the project's own tooling and test surface, so application code should be unaffected.
Source: https://github.com/fastapi/fastapi/releases/tag/0.143.2