diff --git a/actix-files/src/chunked.rs b/actix-files/src/chunked.rs
index fbb46e417..68221ccc3 100644
--- a/actix-files/src/chunked.rs
+++ b/actix-files/src/chunked.rs
@@ -6,8 +6,7 @@ use std::{
     task::{Context, Poll},
 };
 
-use actix_web::error::Error;
-use bytes::Bytes;
+use actix_web::{error::Error, web::Bytes};
 use futures_core::{ready, Stream};
 use pin_project_lite::pin_project;
 
diff --git a/actix-files/src/named.rs b/actix-files/src/named.rs
index 2026868ec..e938f8c05 100644
--- a/actix-files/src/named.rs
+++ b/actix-files/src/named.rs
@@ -13,6 +13,7 @@ use std::os::unix::fs::MetadataExt;
 use actix_http::body::AnyBody;
 use actix_service::{Service, ServiceFactory};
 use actix_web::{
+    body::BoxBody,
     dev::{
         AppService, BodyEncoding, HttpServiceFactory, ResourceDef, ServiceRequest,
         ServiceResponse, SizedStream,
@@ -394,7 +395,7 @@ impl NamedFile {
     }
 
     /// Creates an `HttpResponse` with file as a streaming body.
-    pub fn into_response(self, req: &HttpRequest) -> HttpResponse {
+    pub fn into_response(self, req: &HttpRequest) -> HttpResponse<BoxBody> {
         if self.status_code != StatusCode::OK {
             let mut res = HttpResponse::build(self.status_code);
 
@@ -598,7 +599,10 @@ impl DerefMut for NamedFile {
 }
 
 impl Responder for NamedFile {
-    fn respond_to(self, req: &HttpRequest) -> HttpResponse {
+    // TODO: can be improved
+    type Body = BoxBody;
+
+    fn respond_to(self, req: &HttpRequest) -> HttpResponse<Self::Body> {
         self.into_response(req)
     }
 }
diff --git a/actix-http/src/body/either.rs b/actix-http/src/body/either.rs
index 418d3a696..38f164762 100644
--- a/actix-http/src/body/either.rs
+++ b/actix-http/src/body/either.rs
@@ -77,7 +77,10 @@ mod tests {
     use super::*;
 
     #[test]
-    fn either_body_works() {
-        let _body = EitherBody::new(());
+    fn type_parameter_inference() {
+        let _body: EitherBody<(), _> = EitherBody::new(());
+
+        let _body: EitherBody<_, ()> = EitherBody::left(());
+        let _body: EitherBody<(), _> = EitherBody::right(());
     }
 }
diff --git a/actix-http/src/body/message_body.rs b/actix-http/src/body/message_body.rs
index e1d928bc9..5021ff832 100644
--- a/actix-http/src/body/message_body.rs
+++ b/actix-http/src/body/message_body.rs
@@ -13,7 +13,8 @@ use pin_project_lite::pin_project;
 
 use super::BodySize;
 
-/// An interface for response bodies.
+/// An interface types that can converted to bytes and used as response bodies.
+// TODO: examples
 pub trait MessageBody {
     type Error;
 
diff --git a/actix-http/src/body/size.rs b/actix-http/src/body/size.rs
index e238eadac..d64af9d44 100644
--- a/actix-http/src/body/size.rs
+++ b/actix-http/src/body/size.rs
@@ -18,7 +18,7 @@ pub enum BodySize {
 }
 
 impl BodySize {
-    /// Returns true if size hint indicates no or empty body.
+    /// Returns true if size hint indicates omitted or empty body.
     ///
     /// Streams will return false because it cannot be known without reading the stream.
     ///
diff --git a/src/error/internal.rs b/src/error/internal.rs
index 00b77586e..c766ba83e 100644
--- a/src/error/internal.rs
+++ b/src/error/internal.rs
@@ -109,7 +109,9 @@ impl<T> Responder for InternalError<T>
 where
     T: fmt::Debug + fmt::Display + 'static,
 {
-    fn respond_to(self, _: &HttpRequest) -> HttpResponse {
+    type Body = BoxBody;
+
+    fn respond_to(self, _: &HttpRequest) -> HttpResponse<Self::Body> {
         HttpResponse::from_error(self)
     }
 }
diff --git a/src/handler.rs b/src/handler.rs
index ddefe8d53..375f8abee 100644
--- a/src/handler.rs
+++ b/src/handler.rs
@@ -6,6 +6,7 @@ use actix_service::{
 };
 
 use crate::{
+    body::EitherBody,
     service::{ServiceRequest, ServiceResponse},
     Error, FromRequest, HttpResponse, Responder,
 };
@@ -26,7 +27,13 @@ where
 
 pub fn handler_service<F, T, R>(
     handler: F,
-) -> BoxServiceFactory<(), ServiceRequest, ServiceResponse, Error, ()>
+) -> BoxServiceFactory<
+    (),
+    ServiceRequest,
+    ServiceResponse<EitherBody<<R::Output as Responder>::Body>>,
+    Error,
+    (),
+>
 where
     F: Handler<T, R>,
     T: FromRequest,
@@ -35,12 +42,21 @@ where
 {
     boxed::factory(fn_service(move |req: ServiceRequest| {
         let handler = handler.clone();
+
         async move {
             let (req, mut payload) = req.into_parts();
             let res = match T::from_request(&req, &mut payload).await {
-                Err(err) => HttpResponse::from_error(err),
-                Ok(data) => handler.call(data).await.respond_to(&req),
+                Err(err) => {
+                    HttpResponse::from_error(err).map_body(|_, body| EitherBody::right(body))
+                }
+
+                Ok(data) => handler
+                    .call(data)
+                    .await
+                    .respond_to(&req)
+                    .map_body(|_, body| EitherBody::left(body)),
             };
+
             Ok(ServiceResponse::new(req, res))
         }
     }))
diff --git a/src/resource.rs b/src/resource.rs
index a025a8943..bd9518bd0 100644
--- a/src/resource.rs
+++ b/src/resource.rs
@@ -1,7 +1,4 @@
-use std::cell::RefCell;
-use std::fmt;
-use std::future::Future;
-use std::rc::Rc;
+use std::{cell::RefCell, error::Error as StdError, fmt, future::Future, rc::Rc};
 
 use actix_http::Extensions;
 use actix_router::{IntoPatterns, Patterns};
@@ -13,6 +10,7 @@ use futures_core::future::LocalBoxFuture;
 use futures_util::future::join_all;
 
 use crate::{
+    body::MessageBody,
     data::Data,
     dev::{ensure_leading_slash, AppService, ResourceDef},
     guard::Guard,
@@ -241,6 +239,9 @@ where
         I: FromRequest + 'static,
         R: Future + 'static,
         R::Output: Responder + 'static,
+        <R::Output as Responder>::Body: MessageBody + 'static,
+        <<R::Output as Responder>::Body as MessageBody>::Error:
+            Into<Box<dyn StdError + 'static>>,
     {
         self.routes.push(Route::new().to(handler));
         self
diff --git a/src/responder.rs b/src/responder.rs
index e78d0c1c7..2878c1992 100644
--- a/src/responder.rs
+++ b/src/responder.rs
@@ -1,5 +1,7 @@
+use std::error::Error as StdError;
+
 use actix_http::{
-    body::BoxBody,
+    body::{BoxBody, EitherBody, MessageBody},
     http::{header::IntoHeaderPair, Error as HttpError, HeaderMap, StatusCode},
 };
 use bytes::{Bytes, BytesMut};
@@ -10,8 +12,10 @@ use crate::{Error, HttpRequest, HttpResponse, HttpResponseBuilder};
 ///
 /// Any types that implement this trait can be used in the return type of a handler.
 pub trait Responder {
+    type Body: MessageBody + 'static;
+
     /// Convert self to `HttpResponse`.
-    fn respond_to(self, req: &HttpRequest) -> HttpResponse<BoxBody>;
+    fn respond_to(self, req: &HttpRequest) -> HttpResponse<Self::Body>;
 
     /// Override a status code for a Responder.
     ///
@@ -57,38 +61,56 @@ pub trait Responder {
 }
 
 impl Responder for HttpResponse {
+    type Body = BoxBody;
+
     #[inline]
-    fn respond_to(self, _: &HttpRequest) -> HttpResponse<BoxBody> {
+    fn respond_to(self, _: &HttpRequest) -> HttpResponse<Self::Body> {
         self
     }
 }
 
 impl Responder for actix_http::Response<BoxBody> {
+    type Body = BoxBody;
+
     #[inline]
-    fn respond_to(self, _: &HttpRequest) -> HttpResponse<BoxBody> {
+    fn respond_to(self, _: &HttpRequest) -> HttpResponse<Self::Body> {
         HttpResponse::from(self)
     }
 }
 
 impl Responder for HttpResponseBuilder {
+    type Body = BoxBody;
+
     #[inline]
-    fn respond_to(mut self, _: &HttpRequest) -> HttpResponse<BoxBody> {
+    fn respond_to(mut self, _: &HttpRequest) -> HttpResponse<Self::Body> {
         self.finish()
     }
 }
 
 impl Responder for actix_http::ResponseBuilder {
+    type Body = BoxBody;
+
     #[inline]
-    fn respond_to(mut self, req: &HttpRequest) -> HttpResponse<BoxBody> {
+    fn respond_to(mut self, req: &HttpRequest) -> HttpResponse<Self::Body> {
         self.finish().map_into_boxed_body().respond_to(req)
     }
 }
 
-impl<T: Responder> Responder for Option<T> {
-    fn respond_to(self, req: &HttpRequest) -> HttpResponse<BoxBody> {
+impl<T> Responder for Option<T>
+where
+    T: Responder,
+    <T::Body as MessageBody>::Error: Into<Box<dyn StdError + 'static>>,
+{
+    type Body = EitherBody<T::Body>;
+
+    fn respond_to(self, req: &HttpRequest) -> HttpResponse<Self::Body> {
         match self {
-            Some(val) => val.respond_to(req),
-            None => HttpResponse::new(StatusCode::NOT_FOUND),
+            Some(val) => val
+                .respond_to(req)
+                .map_body(|_, body| EitherBody::left(body)),
+
+            None => HttpResponse::new(StatusCode::NOT_FOUND)
+                .map_body(|_, body| EitherBody::right(body)),
         }
     }
 }
@@ -96,48 +118,78 @@ impl<T: Responder> Responder for Option<T> {
 impl<T, E> Responder for Result<T, E>
 where
     T: Responder,
+    <T::Body as MessageBody>::Error: Into<Box<dyn StdError + 'static>>,
     E: Into<Error>,
 {
-    fn respond_to(self, req: &HttpRequest) -> HttpResponse<BoxBody> {
+    type Body = EitherBody<T::Body>;
+
+    fn respond_to(self, req: &HttpRequest) -> HttpResponse<Self::Body> {
         match self {
-            Ok(val) => val.respond_to(req),
-            Err(e) => HttpResponse::from_error(e.into()),
+            Ok(val) => val
+                .respond_to(req)
+                .map_body(|_, body| EitherBody::left(body)),
+
+            Err(e) => {
+                HttpResponse::from_error(e.into()).map_body(|_, body| EitherBody::right(body))
+            }
         }
     }
 }
 
 impl<T: Responder> Responder for (T, StatusCode) {
-    fn respond_to(self, req: &HttpRequest) -> HttpResponse<BoxBody> {
+    type Body = T::Body;
+
+    fn respond_to(self, req: &HttpRequest) -> HttpResponse<Self::Body> {
         let mut res = self.0.respond_to(req);
         *res.status_mut() = self.1;
         res
     }
 }
 
-macro_rules! impl_responder {
-    ($res: ty, $ct: path) => {
+macro_rules! impl_responder_by_forward_into_base_response {
+    ($res:ty, $body:ty) => {
         impl Responder for $res {
-            fn respond_to(self, _: &HttpRequest) -> HttpResponse<BoxBody> {
-                HttpResponse::Ok().content_type($ct).body(self)
+            type Body = $body;
+
+            fn respond_to(self, _: &HttpRequest) -> HttpResponse<Self::Body> {
+                let res: actix_http::Response<_> = self.into();
+                res.into()
             }
         }
     };
+
+    ($res:ty) => {
+        impl_responder_by_forward_into_base_response!($res, $res);
+    };
 }
 
-impl_responder!(&'static str, mime::TEXT_PLAIN_UTF_8);
+impl_responder_by_forward_into_base_response!(&'static [u8]);
+impl_responder_by_forward_into_base_response!(Bytes);
+impl_responder_by_forward_into_base_response!(BytesMut);
 
-impl_responder!(String, mime::TEXT_PLAIN_UTF_8);
+impl_responder_by_forward_into_base_response!(&'static str);
+impl_responder_by_forward_into_base_response!(String);
+
+// macro_rules! impl_responder {
+//     ($res:ty, $body:ty, $ct:path) => {
+//         impl Responder for $res {
+//             type Body = $body;
+
+//             fn respond_to(self, _: &HttpRequest) -> HttpResponse<Self::Body> {
+//                 HttpResponse::Ok().content_type($ct).body(self)
+//             }
+//         }
+//     };
+
+//     ($res:ty, $ct:path) => {
+//         impl_responder!($res, $res, $ct);
+//     };
+// }
 
 // impl_responder!(&'_ String, mime::TEXT_PLAIN_UTF_8);
 
 // impl_responder!(Cow<'_, str>, mime::TEXT_PLAIN_UTF_8);
 
-impl_responder!(&'static [u8], mime::APPLICATION_OCTET_STREAM);
-
-impl_responder!(Bytes, mime::APPLICATION_OCTET_STREAM);
-
-impl_responder!(BytesMut, mime::APPLICATION_OCTET_STREAM);
-
 /// Allows overriding status code and headers for a responder.
 pub struct CustomResponder<T> {
     responder: T,
@@ -202,11 +254,20 @@ impl<T: Responder> CustomResponder<T> {
     }
 }
 
-impl<T: Responder> Responder for CustomResponder<T> {
-    fn respond_to(self, req: &HttpRequest) -> HttpResponse {
+impl<T> Responder for CustomResponder<T>
+where
+    T: Responder,
+    <T::Body as MessageBody>::Error: Into<Box<dyn StdError + 'static>>,
+{
+    type Body = EitherBody<T::Body>;
+
+    fn respond_to(self, req: &HttpRequest) -> HttpResponse<Self::Body> {
         let headers = match self.headers {
             Ok(headers) => headers,
-            Err(err) => return HttpResponse::from_error(Error::from(err)),
+            Err(err) => {
+                return HttpResponse::from_error(Error::from(err))
+                    .map_body(|_, body| EitherBody::right(body))
+            }
         };
 
         let mut res = self.responder.respond_to(req);
@@ -220,7 +281,7 @@ impl<T: Responder> Responder for CustomResponder<T> {
             res.headers_mut().insert(k, v);
         }
 
-        res
+        res.map_body(|_, body| EitherBody::left(body))
     }
 }
 
diff --git a/src/response/builder.rs b/src/response/builder.rs
index 21364444c..db493b69f 100644
--- a/src/response/builder.rs
+++ b/src/response/builder.rs
@@ -306,7 +306,7 @@ impl HttpResponseBuilder {
             .extensions_mut()
     }
 
-    /// Set a body and generate `Response`.
+    /// Set a body and build the `HttpResponse`.
     ///
     /// `HttpResponseBuilder` can not be used after this call.
     pub fn body<B>(&mut self, body: B) -> HttpResponse<BoxBody>
@@ -320,7 +320,7 @@ impl HttpResponseBuilder {
         }
     }
 
-    /// Set a body and generate `Response`.
+    /// Set a body and build the `HttpResponse`.
     ///
     /// `HttpResponseBuilder` can not be used after this call.
     pub fn message_body<B>(&mut self, body: B) -> Result<HttpResponse<B>, Error> {
@@ -350,7 +350,7 @@ impl HttpResponseBuilder {
         Ok(res)
     }
 
-    /// Set a streaming body and generate `Response`.
+    /// Set a streaming body and build the `HttpResponse`.
     ///
     /// `HttpResponseBuilder` can not be used after this call.
     #[inline]
@@ -362,7 +362,7 @@ impl HttpResponseBuilder {
         self.body(BoxBody::new(BodyStream::new(stream)))
     }
 
-    /// Set a json body and generate `Response`
+    /// Set a JSON body and build the `HttpResponse`.
     ///
     /// `HttpResponseBuilder` can not be used after this call.
     pub fn json(&mut self, value: impl Serialize) -> HttpResponse {
@@ -384,7 +384,7 @@ impl HttpResponseBuilder {
         }
     }
 
-    /// Set an empty body and generate `Response`
+    /// Set an empty body and build the `HttpResponse`.
     ///
     /// `HttpResponseBuilder` can not be used after this call.
     #[inline]
diff --git a/src/route.rs b/src/route.rs
index 0c0699430..66fda5068 100644
--- a/src/route.rs
+++ b/src/route.rs
@@ -1,6 +1,6 @@
 #![allow(clippy::rc_buffer)] // inner value is mutated before being shared (`Rc::get_mut`)
 
-use std::{future::Future, rc::Rc};
+use std::{error::Error as StdError, future::Future, mem, rc::Rc};
 
 use actix_http::http::Method;
 use actix_service::{
@@ -10,6 +10,7 @@ use actix_service::{
 use futures_core::future::LocalBoxFuture;
 
 use crate::{
+    body::MessageBody,
     guard::{self, Guard},
     handler::{handler_service, Handler},
     service::{ServiceRequest, ServiceResponse},
@@ -30,13 +31,16 @@ impl Route {
     #[allow(clippy::new_without_default)]
     pub fn new() -> Route {
         Route {
-            service: handler_service(HttpResponse::NotFound),
+            // TODO: remove double boxing
+            service: boxed::factory(
+                handler_service(HttpResponse::NotFound).map(|res| res.map_into_boxed_body()),
+            ),
             guards: Rc::new(Vec::new()),
         }
     }
 
     pub(crate) fn take_guards(&mut self) -> Vec<Box<dyn Guard>> {
-        std::mem::take(Rc::get_mut(&mut self.guards).unwrap())
+        mem::take(Rc::get_mut(&mut self.guards).unwrap())
     }
 }
 
@@ -181,8 +185,13 @@ impl Route {
         T: FromRequest + 'static,
         R: Future + 'static,
         R::Output: Responder + 'static,
+        <R::Output as Responder>::Body: MessageBody + 'static,
+        <<R::Output as Responder>::Body as MessageBody>::Error:
+            Into<Box<dyn StdError + 'static>>,
     {
-        self.service = handler_service(handler);
+        // TODO: remove double boxing
+        self.service =
+            boxed::factory(handler_service(handler).map(|res| res.map_into_boxed_body()));
         self
     }
 
diff --git a/src/server.rs b/src/server.rs
index 1bf56655b..2510dbba2 100644
--- a/src/server.rs
+++ b/src/server.rs
@@ -656,8 +656,8 @@ fn create_tcp_listener(addr: net::SocketAddr, backlog: u32) -> io::Result<net::T
     Ok(net::TcpListener::from(socket))
 }
 
-#[cfg(feature = "openssl")]
 /// Configure `SslAcceptorBuilder` with custom server flags.
+#[cfg(feature = "openssl")]
 fn openssl_acceptor(mut builder: SslAcceptorBuilder) -> io::Result<SslAcceptor> {
     builder.set_alpn_select_callback(|_, protocols| {
         const H2: &[u8] = b"\x02h2";
diff --git a/src/types/either.rs b/src/types/either.rs
index 0a8a90133..df6d2f9c7 100644
--- a/src/types/either.rs
+++ b/src/types/either.rs
@@ -1,6 +1,7 @@
 //! For either helper, see [`Either`].
 
 use std::{
+    error::Error as StdError,
     future::Future,
     mem,
     pin::Pin,
@@ -12,7 +13,7 @@ use futures_core::ready;
 use pin_project_lite::pin_project;
 
 use crate::{
-    dev,
+    body, dev,
     web::{Form, Json},
     Error, FromRequest, HttpRequest, HttpResponse, Responder,
 };
@@ -144,12 +145,21 @@ impl<L, R> Either<L, R> {
 impl<L, R> Responder for Either<L, R>
 where
     L: Responder,
+    <L::Body as dev::MessageBody>::Error: Into<Box<dyn StdError + 'static>>,
     R: Responder,
+    <R::Body as dev::MessageBody>::Error: Into<Box<dyn StdError + 'static>>,
 {
-    fn respond_to(self, req: &HttpRequest) -> HttpResponse {
+    type Body = body::EitherBody<L::Body, R::Body>;
+
+    fn respond_to(self, req: &HttpRequest) -> HttpResponse<Self::Body> {
         match self {
-            Either::Left(a) => a.respond_to(req),
-            Either::Right(b) => b.respond_to(req),
+            Either::Left(a) => a
+                .respond_to(req)
+                .map_body(|_, body| body::EitherBody::left(body)),
+
+            Either::Right(b) => b
+                .respond_to(req)
+                .map_body(|_, body| body::EitherBody::right(body)),
         }
     }
 }
diff --git a/src/types/form.rs b/src/types/form.rs
index f4414dec5..3603ca2dd 100644
--- a/src/types/form.rs
+++ b/src/types/form.rs
@@ -20,8 +20,9 @@ use serde::{de::DeserializeOwned, Serialize};
 #[cfg(feature = "__compress")]
 use crate::dev::Decompress;
 use crate::{
-    error::UrlencodedError, extract::FromRequest, http::header::CONTENT_LENGTH, web, Error,
-    HttpMessage, HttpRequest, HttpResponse, Responder,
+    body::EitherBody, error::UrlencodedError, extract::FromRequest,
+    http::header::CONTENT_LENGTH, web, Error, HttpMessage, HttpRequest, HttpResponse,
+    Responder,
 };
 
 /// URL encoded payload extractor and responder.
@@ -180,12 +181,22 @@ impl<T: fmt::Display> fmt::Display for Form<T> {
 
 /// See [here](#responder) for example of usage as a handler return type.
 impl<T: Serialize> Responder for Form<T> {
-    fn respond_to(self, _: &HttpRequest) -> HttpResponse {
+    type Body = EitherBody<String>;
+
+    fn respond_to(self, _: &HttpRequest) -> HttpResponse<Self::Body> {
         match serde_urlencoded::to_string(&self.0) {
-            Ok(body) => HttpResponse::Ok()
+            Ok(body) => match HttpResponse::Ok()
                 .content_type(mime::APPLICATION_WWW_FORM_URLENCODED)
-                .body(body),
-            Err(err) => HttpResponse::from_error(UrlencodedError::Serialize(err)),
+                .message_body(body)
+            {
+                Ok(res) => res.map_body(|_, body| EitherBody::left(body)),
+                Err(err) => {
+                    HttpResponse::from_error(err).map_body(|_, body| EitherBody::right(body))
+                }
+            },
+
+            Err(err) => HttpResponse::from_error(UrlencodedError::Serialize(err))
+                .map_body(|_, body| EitherBody::right(body)),
         }
     }
 }
diff --git a/src/types/json.rs b/src/types/json.rs
index 92f53deab..568cf70fb 100644
--- a/src/types/json.rs
+++ b/src/types/json.rs
@@ -19,6 +19,7 @@ use actix_http::Payload;
 #[cfg(feature = "__compress")]
 use crate::dev::Decompress;
 use crate::{
+    body::EitherBody,
     error::{Error, JsonPayloadError},
     extract::FromRequest,
     http::header::CONTENT_LENGTH,
@@ -116,12 +117,22 @@ impl<T: Serialize> Serialize for Json<T> {
 ///
 /// If serialization failed
 impl<T: Serialize> Responder for Json<T> {
-    fn respond_to(self, _: &HttpRequest) -> HttpResponse {
+    type Body = EitherBody<String>;
+
+    fn respond_to(self, _: &HttpRequest) -> HttpResponse<Self::Body> {
         match serde_json::to_string(&self.0) {
-            Ok(body) => HttpResponse::Ok()
+            Ok(body) => match HttpResponse::Ok()
                 .content_type(mime::APPLICATION_JSON)
-                .body(body),
-            Err(err) => HttpResponse::from_error(JsonPayloadError::Serialize(err)),
+                .message_body(body)
+            {
+                Ok(res) => res.map_body(|_, body| EitherBody::left(body)),
+                Err(err) => {
+                    HttpResponse::from_error(err).map_body(|_, body| EitherBody::right(body))
+                }
+            },
+
+            Err(err) => HttpResponse::from_error(JsonPayloadError::Serialize(err))
+                .map_body(|_, body| EitherBody::right(body)),
         }
     }
 }
diff --git a/src/web.rs b/src/web.rs
index e9f5c8518..b58adc2f8 100644
--- a/src/web.rs
+++ b/src/web.rs
@@ -1,14 +1,14 @@
 //! Essentials helper functions and types for application registration.
 
-use std::future::Future;
+use std::{error::Error as StdError, future::Future};
 
 use actix_http::http::Method;
 use actix_router::IntoPatterns;
 pub use bytes::{Buf, BufMut, Bytes, BytesMut};
 
 use crate::{
-    error::BlockingError, extract::FromRequest, handler::Handler, resource::Resource,
-    responder::Responder, route::Route, scope::Scope, service::WebService,
+    body::MessageBody, error::BlockingError, extract::FromRequest, handler::Handler,
+    resource::Resource, responder::Responder, route::Route, scope::Scope, service::WebService,
 };
 
 pub use crate::config::ServiceConfig;
@@ -145,6 +145,8 @@ where
     I: FromRequest + 'static,
     R: Future + 'static,
     R::Output: Responder + 'static,
+    <R::Output as Responder>::Body: MessageBody + 'static,
+    <<R::Output as Responder>::Body as MessageBody>::Error: Into<Box<dyn StdError + 'static>>,
 {
     Route::new().to(handler)
 }