The wrapped receive() did not return anything.

sentry_sdk/integrations/starlette.py

@@ -106,7 +106,7 @@ async def _sentry_receive(*args, **kwargs):
                         description=receive.__qualname__,
                     ) as span:
                         span.set_tag("starlette.middleware_name", middleware_name)
-                        await receive(*args, **kwargs)
+                        return await receive(*args, **kwargs)
 
                 receive_patched = receive.__name__ == "_sentry_receive"
                 new_receive = _sentry_receive if not receive_patched else receive
@@ -119,15 +119,15 @@ async def _sentry_send(*args, **kwargs):
                         op=OP.MIDDLEWARE_STARLETTE_SEND, description=send.__qualname__
                     ) as span:
                         span.set_tag("starlette.middleware_name", middleware_name)
-                        await send(*args, **kwargs)
+                        return await send(*args, **kwargs)
 
                 send_patched = send.__name__ == "_sentry_send"
                 new_send = _sentry_send if not send_patched else send
 
-                await old_call(app, scope, new_receive, new_send, **kwargs)
+                return await old_call(app, scope, new_receive, new_send, **kwargs)
 
         else:
-            await old_call(app, scope, receive, send, **kwargs)
+            return await old_call(app, scope, receive, send, **kwargs)
 
     not_yet_patched = old_call.__name__ not in [
         "_create_span_call",

tests/integrations/starlette/test_starlette.py

@@ -174,6 +174,21 @@ async def do_stuff(message):
         await self.app(scope, receive, do_stuff)
 
 
+class SampleReceiveSendMiddleware:
+    def __init__(self, app):
+        self.app = app
+
+    async def __call__(self, scope, receive, send):
+        message = await receive()
+        assert message
+        assert message["type"] == "http.request"
+
+        send_output = await send({"type": "something-unimportant"})
+        assert send_output is None
+
+        await self.app(scope, receive, send)
+
+
 @pytest.mark.asyncio
 async def test_starlettrequestextractor_content_length(sentry_init):
     with mock.patch(
@@ -644,6 +659,25 @@ def test_middleware_callback_spans(sentry_init, capture_events):
         idx += 1
 
 
+@pytest.mark.asyncio
+async def test_middleware_receive_send(sentry_init, capture_events):
+    sentry_init(
+        traces_sample_rate=1.0,
+        integrations=[StarletteIntegration()],
+    )
+    starlette_app = starlette_app_factory(
+        middleware=[Middleware(SampleReceiveSendMiddleware)]
+    )
+
+    client = TestClient(starlette_app, raise_server_exceptions=False)
+    try:
+        # NOTE: the assert statements checking
+        # for correct behaviour are in `SampleReceiveSendMiddleware`!
+        client.get("/message", auth=("Gabriela", "hello123"))
+    except Exception:
+        pass
+
+
 def test_last_event_id(sentry_init, capture_events):
     sentry_init(
         integrations=[StarletteIntegration()],