10 curated breaking changes across major versions of fastapi. Use this as a migration checklist before bumping dependencies.
ποΈ Add `strict_content_type` checking for JSON requests. PR [#14978](https://github.com/fastapi/fastapi/pull/14978) by [@tiangolo](https://github.com/tiangolo).
Now FastAPI checks, by default, that JSON requests have a `Content-Type` header with a valid JSON value, like `application/json`, and rejects requests that don't.
If the clients for your app don't send a valid `Content-Type` header you can disable this with `strict_content_type=False`.
Check the new docs: [Strict Content-Type Checking](https://fastapi.tiangolo.com/advanced/strict-content-type/).
Get this data programmatically \u2014 free, no authentication.
curl https://depscope.dev/api/breaking/pypi/fastapiποΈ Deprecate `ORJSONResponse` and `UJSONResponse`. PR [#14964](https://github.com/fastapi/fastapi/pull/14964) by [@tiangolo](https://github.com/tiangolo).
β Drop support for Python 3.9. PR [#14897](https://github.com/fastapi/fastapi/pull/14897) by [@tiangolo](https://github.com/tiangolo).
β Drop support for `pydantic.v1`. PR [#14609](https://github.com/fastapi/fastapi/pull/14609) by [@tiangolo](https://github.com/tiangolo).
π Add deprecation warnings when using `pydantic.v1`. PR [#14583](https://github.com/fastapi/fastapi/pull/14583) by [@tiangolo](https://github.com/tiangolo).
π§ Drop support for Python 3.8. PR [#14563](https://github.com/fastapi/fastapi/pull/14563) by [@tiangolo](https://github.com/tiangolo).
This would actually not be a _breaking_ change as no code would really break. Any Python 3.8 installer would just refuse to install the latest version of FastAPI and would only install 0.124.4. Only marking it as a "breaking change" to make it visible.