FastAPI version 0.137.1 has been released with two important fixes. The first resolves typing checks for APIRoute (PR #15765 by @tiangolo). Previously, certain type annotations could cause errors when defining routes via APIRoute; this update ensures that typing behaves correctly.
Additionally, a bug was fixed that prevented using an empty path ("") in path operations when a router does not have a prefix (PR #15763 by @tiangolo). Now developers can define routes with an empty path on prefixless routers, which is useful for root endpoints or when combining routers.
These fixes improve the robustness of FastAPI's routing and typing system, particularly for complex applications that rely on custom APIRoute subclasses or routers without prefixes. No breaking changes are included, so upgrading is safe.
Source: https://github.com/fastapi/fastapi/releases/tag/0.137.1