🔖 Release version 0.137.1 (#15766)

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docs/en/docs/release-notes.md

@@ -7,6 +7,13 @@ hide:
 
 ## Latest Changes
 
+## 0.137.1 (2026-06-15)
+
+### Fixes
+
+* 🚨 Fix typing checks for APIRoute. PR [#15765](https://github.com/fastapi/fastapi/pull/15765) by [@tiangolo](https://github.com/tiangolo).
+* 🐛 Fix bug, allow empty path in path operation in prefixless router. PR [#15763](https://github.com/fastapi/fastapi/pull/15763) by [@tiangolo](https://github.com/tiangolo).
+
 ## 0.137.0 (2026-06-14)
 
 ### Breaking Changes

fastapi/__init__.py

@@ -1,6 +1,6 @@
 """FastAPI framework, high performance, easy to learn, fast to code, ready for production"""
 
-__version__ = "0.137.0"
+__version__ = "0.137.1"
 
 from starlette import status as status
 

fastapi/routing.py

@@ -1062,6 +1062,41 @@ def _populate_api_route_state(
 
 
 class APIRoute(routing.Route):
+    stream_item_type: Any | None
+    response_model: Any
+    summary: str | None
+    response_description: str
+    deprecated: bool | None
+    operation_id: str | None
+    response_model_include: IncEx | None
+    response_model_exclude: IncEx | None
+    response_model_by_alias: bool
+    response_model_exclude_unset: bool
+    response_model_exclude_defaults: bool
+    response_model_exclude_none: bool
+    include_in_schema: bool
+    response_class: type[Response] | DefaultPlaceholder
+    dependency_overrides_provider: Any | None
+    callbacks: list[BaseRoute] | None
+    openapi_extra: dict[str, Any] | None
+    generate_unique_id_function: Callable[[Any], str] | DefaultPlaceholder
+    strict_content_type: bool | DefaultPlaceholder
+    tags: list[str | Enum]
+    responses: dict[int | str, dict[str, Any]]
+    unique_id: str
+    status_code: int | None
+    response_field: ModelField | None
+    stream_item_field: ModelField | None
+    dependencies: list[params.Depends]
+    description: str
+    response_fields: dict[int | str, ModelField]
+    dependant: Dependant
+    _flat_dependant: Dependant
+    _embed_body_fields: bool
+    body_field: ModelField | None
+    is_sse_stream: bool
+    is_json_stream: bool
+
     def __init__(
         self,
         path: str,
@@ -2435,9 +2470,16 @@ class APIRouter(routing.Router):
                 "A path prefix must not end with '/', as the routes will start with '/'"
             )
         else:
-            for r in _iter_included_route_candidates(router.routes):
-                path = getattr(r, "path", None)
-                name = getattr(r, "name", "unknown")
+            for route, route_context in _iter_routes_with_context(router.routes):
+                if route_context is None:
+                    path = getattr(route, "path", None)
+                    name = getattr(route, "name", "unknown")
+                elif route_context.starlette_route is not None:
+                    path = getattr(route_context.starlette_route, "path", None)
+                    name = getattr(route_context.starlette_route, "name", "unknown")
+                else:
+                    path = route_context.path
+                    name = route_context.name
                 if path is not None and not path:
                     raise FastAPIError(
                         f"Prefix and path cannot be both empty (path operation: {name})"

tests/test_router_include_context.py

@@ -2,6 +2,7 @@ from typing import Annotated, cast
 
 import pytest
 from fastapi import APIRouter, Body, Depends, FastAPI, Request
+from fastapi.exceptions import FastAPIError
 from fastapi.responses import HTMLResponse, JSONResponse, PlainTextResponse
 from fastapi.routing import (
     APIRoute,
@@ -807,6 +808,60 @@ def test_no_prefix_include_validation_sees_effective_starlette_route_candidates(
     assert cast(Route, candidates[0]).path == "/child/items"
 
 
+def test_no_prefix_include_validation_sees_effective_api_route_path():
+    leaf_router = APIRouter()
+
+    @leaf_router.get("")
+    def read_items():
+        return []
+
+    parent_router = APIRouter()
+    parent_router.include_router(leaf_router, prefix="/items")
+
+    # for coverage
+    candidates = list(_iter_included_route_candidates(parent_router.routes))
+    assert cast(APIRoute, candidates[0]).path == ""
+
+    app = FastAPI()
+    app.include_router(parent_router)
+    client = TestClient(app)
+
+    response = client.get("/items")
+
+    assert response.status_code == 200, response.text
+    assert response.json() == []
+
+
+def test_no_prefix_include_validation_sees_effective_starlette_route_path():
+    def endpoint(request):
+        return PlainTextResponse("ok")
+
+    child_router = APIRouter(routes=[Route("/items", endpoint, name="read_items")])
+    parent_router = APIRouter()
+    parent_router.include_router(child_router, prefix="/child")
+
+    app = FastAPI()
+    app.include_router(parent_router)
+    client = TestClient(app)
+
+    response = client.get("/child/items")
+
+    assert response.status_code == 200, response.text
+    assert response.text == "ok"
+
+
+def test_no_prefix_include_validation_rejects_empty_effective_api_route_path():
+    router = APIRouter()
+
+    @router.get("")
+    def read_items():  # pragma: no cover
+        return []
+
+    app = FastAPI()
+    with pytest.raises(FastAPIError):
+        app.include_router(router)
+
+
 def test_apirouter_matches_fallback_without_include_context():
     router = APIRouter()