relax bound on MessageBody::Error to Debug

actix-http/src/body/body_stream.rs

@@ -1,5 +1,5 @@
 use std::{
-    error::Error as StdError,
+    fmt,
     pin::Pin,
     task::{Context, Poll},
 };
@@ -25,7 +25,7 @@ pin_project! {
 impl<S, E> BodyStream<S>
 where
     S: Stream<Item = Result<Bytes, E>>,
-    E: Into<Box<dyn StdError>> + 'static,
+    E: fmt::Debug + 'static,
 {
     #[inline]
     pub fn new(stream: S) -> Self {
@@ -36,7 +36,7 @@ where
 impl<S, E> MessageBody for BodyStream<S>
 where
     S: Stream<Item = Result<Bytes, E>>,
-    E: Into<Box<dyn StdError>> + 'static,
+    E: fmt::Debug + 'static,
 {
     type Error = E;
 
@@ -150,21 +150,6 @@ mod tests {
         assert!(matches!(to_bytes(body).await, Err("stringy error")));
     }
 
-    #[actix_rt::test]
-    async fn stream_boxed_error() {
-        // `Box<dyn Error>` does not impl `Error`
-        // but it does impl `Into<Box<dyn Error>>`
-
-        let body = BodyStream::new(stream::once(async {
-            Err(Box::<dyn StdError>::from("stringy error"))
-        }));
-
-        assert_eq!(
-            to_bytes(body).await.unwrap_err().to_string(),
-            "stringy error"
-        );
-    }
-
     #[actix_rt::test]
     async fn stream_delayed_error() {
         let body = BodyStream::new(stream::iter(vec![Ok(Bytes::from("1")), Err(StreamErr)]));

actix-http/src/body/boxed.rs

@@ -1,5 +1,4 @@
 use std::{
-    error::Error as StdError,
     fmt,
     pin::Pin,
     task::{Context, Poll},
@@ -8,23 +7,28 @@ use std::{
 use bytes::Bytes;
 
 use super::{BodySize, MessageBody, MessageBodyMapErr};
-use crate::Error;
 
 /// A boxed message body with boxed errors.
-pub struct BoxBody(Pin<Box<dyn MessageBody<Error = Box<dyn StdError>>>>);
+pub struct BoxBody(Pin<Box<dyn MessageBody<Error = Box<dyn fmt::Debug>>>>);
 
 impl BoxBody {
     /// Boxes a `MessageBody` and any errors it generates.
+    #[inline]
     pub fn new<B>(body: B) -> Self
     where
         B: MessageBody + 'static,
     {
-        let body = MessageBodyMapErr::new(body, Into::into);
+        fn box_it<T: fmt::Debug + 'static>(it: T) -> Box<dyn fmt::Debug> {
+            Box::new(it)
+        }
+
+        let body = MessageBodyMapErr::new(body, box_it);
         Self(Box::pin(body))
     }
 
     /// Returns a mutable pinned reference to the inner message body type.
-    pub fn as_pin_mut(&mut self) -> Pin<&mut (dyn MessageBody<Error = Box<dyn StdError>>)> {
+    #[inline]
+    pub fn as_pin_mut(&mut self) -> Pin<&mut (dyn MessageBody<Error = Box<dyn fmt::Debug>>)> {
         self.0.as_mut()
     }
 }
@@ -36,22 +40,22 @@ impl fmt::Debug for BoxBody {
 }
 
 impl MessageBody for BoxBody {
-    type Error = Error;
+    type Error = Box<dyn fmt::Debug>;
 
+    #[inline]
     fn size(&self) -> BodySize {
         self.0.size()
     }
 
+    #[inline]
     fn poll_next(
         mut self: Pin<&mut Self>,
         cx: &mut Context<'_>,
     ) -> Poll<Option<Result<Bytes, Self::Error>>> {
-        self.0
-            .as_mut()
-            .poll_next(cx)
-            .map_err(|err| Error::new_body().with_cause(err))
+        self.0.as_mut().poll_next(cx)
     }
 
+    #[inline]
     fn is_complete_body(&self) -> bool {
         self.0.is_complete_body()
     }

actix-http/src/body/either.rs

@@ -66,10 +66,10 @@ where
         match self.project() {
             EitherBodyProj::Left { body } => body
                 .poll_next(cx)
-                .map_err(|err| Error::new_body().with_cause(err)),
+                .map_err(|err| Error::new_body().with_cause(format!("{:?}", err))),
             EitherBodyProj::Right { body } => body
                 .poll_next(cx)
-                .map_err(|err| Error::new_body().with_cause(err)),
+                .map_err(|err| Error::new_body().with_cause(format!("{:?}", err))),
         }
     }
 

actix-http/src/body/message_body.rs

@@ -2,8 +2,7 @@
 
 use std::{
     convert::Infallible,
-    error::Error as StdError,
-    mem,
+    fmt, mem,
     pin::Pin,
     task::{Context, Poll},
 };
@@ -17,9 +16,11 @@ use super::BodySize;
 /// An interface types that can converted to bytes and used as response bodies.
 // TODO: examples
 pub trait MessageBody {
-    // TODO: consider this bound to only fmt::Display since the error type is not really used
-    // and there is an impl for Into<Box<StdError>> on String
-    type Error: Into<Box<dyn StdError>>;
+    /// The type of error that will be returned if streaming response fails.
+    ///
+    /// Since it is not appropriate to generate a response mid-stream, it only requires `Debug` for
+    /// internal logging.
+    type Error: fmt::Debug + 'static;
 
     /// Body size hint.
     fn size(&self) -> BodySize;
@@ -450,7 +451,7 @@ impl<B, F, E> MessageBody for MessageBodyMapErr<B, F>
 where
     B: MessageBody,
     F: FnOnce(B::Error) -> E,
-    E: Into<Box<dyn StdError>>,
+    E: fmt::Debug + 'static,
 {
     type Error = E;
 

actix-http/src/body/sized_stream.rs

@@ -1,5 +1,5 @@
 use std::{
-    error::Error as StdError,
+    fmt,
     pin::Pin,
     task::{Context, Poll},
 };
@@ -25,7 +25,7 @@ pin_project! {
 impl<S, E> SizedStream<S>
 where
     S: Stream<Item = Result<Bytes, E>>,
-    E: Into<Box<dyn StdError>> + 'static,
+    E: fmt::Debug + 'static,
 {
     #[inline]
     pub fn new(size: u64, stream: S) -> Self {
@@ -38,7 +38,7 @@ where
 impl<S, E> MessageBody for SizedStream<S>
 where
     S: Stream<Item = Result<Bytes, E>>,
-    E: Into<Box<dyn StdError>> + 'static,
+    E: fmt::Debug + 'static,
 {
     type Error = E;
 
@@ -147,25 +147,4 @@ mod tests {
         let body = SizedStream::new(1, stream::once(async { Err("stringy error") }));
         assert!(matches!(to_bytes(body).await, Err("stringy error")));
     }
-
-    #[actix_rt::test]
-    async fn stream_boxed_error() {
-        // `Box<dyn Error>` does not impl `Error`
-        // but it does impl `Into<Box<dyn Error>>`
-
-        let body = SizedStream::new(
-            0,
-            stream::once(async { Err(Box::<dyn StdError>::from("stringy error")) }),
-        );
-        assert_eq!(to_bytes(body).await.unwrap(), Bytes::new());
-
-        let body = SizedStream::new(
-            1,
-            stream::once(async { Err(Box::<dyn StdError>::from("stringy error")) }),
-        );
-        assert_eq!(
-            to_bytes(body).await.unwrap_err().to_string(),
-            "stringy error"
-        );
-    }
 }

actix-http/src/encoding/encoder.rs

@@ -129,7 +129,7 @@ where
             }
             EncoderBodyProj::Stream { body } => body
                 .poll_next(cx)
-                .map_err(|err| EncoderError::Body(err.into())),
+                .map_err(|err| EncoderError::Body(format!("{:?}", err).into())),
         }
     }
 

actix-http/src/error.rs

@@ -335,28 +335,27 @@ impl From<PayloadError> for Error {
 #[derive(Debug, Display, Error, From)]
 #[non_exhaustive]
 pub enum DispatchError {
-    /// Service error
+    /// Service error.
     // FIXME: display and error type
     #[display(fmt = "Service Error")]
     Service(#[error(not(source))] Response<BoxBody>),
 
-    /// Body error
-    // FIXME: display and error type
+    /// Body error.
     #[display(fmt = "Body Error")]
-    Body(#[error(not(source))] Box<dyn StdError>),
+    ResponseBody(#[error(not(source))] Box<dyn fmt::Debug>),
 
-    /// Upgrade service error
+    /// Upgrade service error.
     Upgrade,
 
     /// An `io::Error` that occurred while trying to read or write to a network stream.
-    #[display(fmt = "IO error: {}", _0)]
+    #[display(fmt = "IO error")]
     Io(io::Error),
 
-    /// Http request parse error.
-    #[display(fmt = "Parse error: {}", _0)]
+    /// Request parse error.
+    #[display(fmt = "Request parse error")]
     Parse(ParseError),
 
-    /// Http/2 error
+    /// HTTP/2 error.
     #[display(fmt = "{}", _0)]
     H2(h2::Error),
 
@@ -364,23 +363,23 @@ pub enum DispatchError {
     #[display(fmt = "The first request did not complete within the specified timeout")]
     SlowRequestTimeout,
 
-    /// Disconnect timeout. Makes sense for ssl streams.
+    /// Disconnect timeout. Makes sense for TLS streams.
     #[display(fmt = "Connection shutdown timeout")]
     DisconnectTimeout,
 
-    /// Payload is not consumed
+    /// Payload is not consumed.
     #[display(fmt = "Task is completed but request's payload is not consumed")]
     PayloadIsNotConsumed,
 
-    /// Malformed request
+    /// Malformed request.
     #[display(fmt = "Malformed request")]
     MalformedRequest,
 
-    /// Internal error
+    /// Internal error.
     #[display(fmt = "Internal error")]
     InternalError,
 
-    /// Unknown error
+    /// Unknown error.
     #[display(fmt = "Unknown error")]
     Unknown,
 }

actix-http/src/h1/dispatcher.rs

@@ -426,7 +426,7 @@ where
                             }
 
                             Poll::Ready(Some(Err(err))) => {
-                                return Err(DispatchError::Body(err.into()))
+                                return Err(DispatchError::ResponseBody(Box::new(err)))
                             }
 
                             Poll::Pending => return Ok(PollResponse::DoNothing),
@@ -458,7 +458,7 @@ where
                             }
 
                             Poll::Ready(Some(Err(err))) => {
-                                return Err(DispatchError::Service(err.into()))
+                                return Err(DispatchError::ResponseBody(err))
                             }
 
                             Poll::Pending => return Ok(PollResponse::DoNothing),

actix-http/src/h2/dispatcher.rs

@@ -1,6 +1,5 @@
 use std::{
-    cmp,
-    error::Error as StdError,
+    cmp, fmt,
     future::Future,
     marker::PhantomData,
     net,
@@ -14,6 +13,7 @@ use actix_rt::time::{sleep, Sleep};
 use actix_service::Service;
 use actix_utils::future::poll_fn;
 use bytes::{Bytes, BytesMut};
+use derive_more::{Display, Error};
 use futures_core::ready;
 use h2::{
     server::{Connection, SendResponse},
@@ -187,10 +187,25 @@ where
     }
 }
 
+#[derive(Debug, Display, Error)]
 enum DispatchError {
+    /// Send response head failed.
+    #[display(fmt = "Send response head failed")]
     SendResponse(h2::Error),
+
+    /// Send response data failed.
+    #[display(fmt = "Send response data failed")]
     SendData(h2::Error),
-    ResponseBody(Box<dyn StdError>),
+
+    /// Receiving body chunk failed.
+    #[display(fmt = "Receiving body chunk failed")]
+    ResponseBody(#[error(not(source))] Box<dyn fmt::Debug>),
+}
+
+impl DispatchError {
+    fn response_body<E: fmt::Debug + 'static>(err: E) -> Self {
+        Self::ResponseBody(Box::new(err))
+    }
 }
 
 async fn handle_response<B>(
@@ -221,7 +236,7 @@ where
     actix_rt::pin!(body);
 
     while let Some(res) = poll_fn(|cx| body.as_mut().poll_next(cx)).await {
-        let mut chunk = res.map_err(|err| DispatchError::ResponseBody(err.into()))?;
+        let mut chunk = res.map_err(DispatchError::response_body)?;
 
         'send: loop {
             let chunk_size = cmp::min(chunk.len(), CHUNK_SIZE);

awc/src/any_body.rs

@@ -11,8 +11,6 @@ use pin_project_lite::pin_project;
 
 use actix_http::body::{BodySize, BodyStream, BoxBody, MessageBody, SizedStream};
 
-use crate::BoxError;
-
 pin_project! {
     /// Represents various types of HTTP message body.
     #[derive(Clone)]
@@ -117,7 +115,9 @@ where
                 }
             }
 
-            AnyBodyProj::Body { body } => body.poll_next(cx).map_err(|err| err.into()),
+            AnyBodyProj::Body { body } => body
+                .poll_next(cx)
+                .map_err(|err| format!("{:?}", err).into()),
         }
     }
 }
@@ -213,7 +213,7 @@ impl<B> From<BytesMut> for AnyBody<B> {
 impl<S, E> From<SizedStream<S>> for AnyBody
 where
     S: Stream<Item = Result<Bytes, E>> + 'static,
-    E: Into<BoxError> + 'static,
+    E: fmt::Debug + 'static,
 {
     fn from(stream: SizedStream<S>) -> Self {
         AnyBody::new_boxed(stream)
@@ -223,7 +223,7 @@ where
 impl<S, E> From<BodyStream<S>> for AnyBody
 where
     S: Stream<Item = Result<Bytes, E>> + 'static,
-    E: Into<BoxError> + 'static,
+    E: fmt::Debug + 'static,
 {
     fn from(stream: BodyStream<S>) -> Self {
         AnyBody::new_boxed(stream)

awc/src/frozen.rs

@@ -1,4 +1,4 @@
-use std::{convert::TryFrom, net, rc::Rc, time::Duration};
+use std::{convert::TryFrom, fmt, net, rc::Rc, time::Duration};
 
 use bytes::Bytes;
 use futures_core::Stream;
@@ -13,7 +13,7 @@ use actix_http::{
 use crate::{
     any_body::AnyBody,
     sender::{RequestSender, SendClientRequest},
-    BoxError, ClientConfig,
+    ClientConfig,
 };
 
 /// `FrozenClientRequest` struct represents cloneable client request.
@@ -83,7 +83,7 @@ impl FrozenClientRequest {
     pub fn send_stream<S, E>(&self, stream: S) -> SendClientRequest
     where
         S: Stream<Item = Result<Bytes, E>> + Unpin + 'static,
-        E: Into<BoxError> + 'static,
+        E: fmt::Debug + 'static,
     {
         RequestSender::Rc(self.head.clone(), None).send_stream(
             self.addr,
@@ -208,7 +208,7 @@ impl FrozenSendBuilder {
     pub fn send_stream<S, E>(self, stream: S) -> SendClientRequest
     where
         S: Stream<Item = Result<Bytes, E>> + Unpin + 'static,
-        E: Into<BoxError> + 'static,
+        E: fmt::Debug + 'static,
     {
         if let Some(e) = self.err {
             return e.into();

awc/src/request.rs

@@ -15,7 +15,7 @@ use crate::{
     error::{FreezeRequestError, InvalidUrl},
     frozen::FrozenClientRequest,
     sender::{PrepForSendingError, RequestSender, SendClientRequest},
-    BoxError, ClientConfig,
+    ClientConfig,
 };
 
 #[cfg(feature = "cookies")]
@@ -394,7 +394,7 @@ impl ClientRequest {
     pub fn send_stream<S, E>(self, stream: S) -> SendClientRequest
     where
         S: Stream<Item = Result<Bytes, E>> + Unpin + 'static,
-        E: Into<BoxError> + 'static,
+        E: fmt::Debug + 'static,
     {
         let slf = match self.prep_for_sending() {
             Ok(slf) => slf,

awc/src/sender.rs

@@ -1,4 +1,5 @@
 use std::{
+    fmt,
     future::Future,
     net,
     pin::Pin,
@@ -25,7 +26,7 @@ use actix_http::{encoding::Decoder, header::ContentEncoding, Payload, PayloadStr
 use crate::{
     any_body::AnyBody,
     error::{FreezeRequestError, InvalidUrl, SendRequestError},
-    BoxError, ClientConfig, ClientResponse, ConnectRequest, ConnectResponse,
+    ClientConfig, ClientResponse, ConnectRequest, ConnectResponse,
 };
 
 #[derive(Debug, From)]
@@ -275,7 +276,7 @@ impl RequestSender {
     ) -> SendClientRequest
     where
         S: Stream<Item = Result<Bytes, E>> + Unpin + 'static,
-        E: Into<BoxError> + 'static,
+        E: fmt::Debug + 'static,
     {
         self.send_body(
             addr,

src/dev.rs

@@ -3,6 +3,8 @@
 //! Most users will not have to interact with the types in this module, but it is useful for those
 //! writing extractors, middleware, libraries, or interacting with the service API directly.
 
+use std::fmt;
+
 pub use crate::config::{AppConfig, AppService};
 #[doc(hidden)]
 pub use crate::handler::Handler;
@@ -114,7 +116,7 @@ pub(crate) enum AnyBody {
 }
 
 impl crate::body::MessageBody for AnyBody {
-    type Error = crate::BoxError;
+    type Error = Box<dyn fmt::Debug>;
 
     /// Body size hint.
     fn size(&self) -> crate::body::BodySize {

src/handler.rs

@@ -1,11 +1,11 @@
-use std::future::Future;
+use std::{fmt, future::Future};
 
 use actix_service::{boxed, fn_service};
 
 use crate::{
     body::MessageBody,
     service::{BoxedHttpServiceFactory, ServiceRequest, ServiceResponse},
-    BoxError, FromRequest, HttpResponse, Responder,
+    FromRequest, HttpResponse, Responder,
 };
 
 /// A request handler is an async function that accepts zero or more parameters that can be
@@ -31,7 +31,7 @@ where
     R: Future,
     R::Output: Responder,
     <R::Output as Responder>::Body: MessageBody,
-    <<R::Output as Responder>::Body as MessageBody>::Error: Into<BoxError>,
+    <<R::Output as Responder>::Body as MessageBody>::Error: fmt::Debug,
 {
     boxed::factory(fn_service(move |req: ServiceRequest| {
         let handler = handler.clone();

src/lib.rs

@@ -113,5 +113,3 @@ pub use crate::route::Route;
 pub use crate::scope::Scope;
 pub use crate::server::HttpServer;
 pub use crate::types::Either;
-
-pub(crate) type BoxError = Box<dyn std::error::Error>;

src/middleware/logger.rs

@@ -325,9 +325,8 @@ pin_project! {
 impl<B> MessageBody for StreamLog<B>
 where
     B: MessageBody,
-    B::Error: Into<Error>,
 {
-    type Error = Error;
+    type Error = B::Error;
 
     fn size(&self) -> BodySize {
         self.body.size()
@@ -344,7 +343,7 @@ where
                 *this.size += chunk.len();
                 Poll::Ready(Some(Ok(chunk)))
             }
-            Some(Err(err)) => Poll::Ready(Some(Err(err.into()))),
+            Some(Err(err)) => Poll::Ready(Some(Err(err))),
             None => Poll::Ready(None),
         }
     }

src/resource.rs

@@ -20,7 +20,7 @@ use crate::{
         BoxedHttpService, BoxedHttpServiceFactory, HttpServiceFactory, ServiceRequest,
         ServiceResponse,
     },
-    BoxError, Error, FromRequest, HttpResponse, Responder,
+    Error, FromRequest, HttpResponse, Responder,
 };
 
 /// *Resource* is an entry in resources table which corresponds to requested URL.
@@ -239,7 +239,7 @@ where
         R: Future + 'static,
         R::Output: Responder + 'static,
         <R::Output as Responder>::Body: MessageBody,
-        <<R::Output as Responder>::Body as MessageBody>::Error: Into<BoxError>,
+        <<R::Output as Responder>::Body as MessageBody>::Error: fmt::Debug,
     {
         self.routes.push(Route::new().to(handler));
         self

src/response/builder.rs

@@ -1,6 +1,7 @@
 use std::{
     cell::{Ref, RefMut},
     convert::TryInto,
+    fmt,
     future::Future,
     pin::Pin,
     task::{Context, Poll},
@@ -23,7 +24,7 @@ use cookie::{Cookie, CookieJar};
 
 use crate::{
     error::{Error, JsonPayloadError},
-    BoxError, HttpResponse,
+    HttpResponse,
 };
 
 /// An HTTP response builder.
@@ -349,7 +350,7 @@ impl HttpResponseBuilder {
     pub fn streaming<S, E>(&mut self, stream: S) -> HttpResponse
     where
         S: Stream<Item = Result<Bytes, E>> + 'static,
-        E: Into<BoxError> + 'static,
+        E: fmt::Debug + 'static,
     {
         self.body(BodyStream::new(stream))
     }

src/response/customize_responder.rs

@@ -1,3 +1,5 @@
+use std::fmt;
+
 use actix_http::{
     body::{EitherBody, MessageBody},
     error::HttpError,
@@ -6,7 +8,7 @@ use actix_http::{
     StatusCode,
 };
 
-use crate::{BoxError, HttpRequest, HttpResponse, Responder};
+use crate::{HttpRequest, HttpResponse, Responder};
 
 /// Allows overriding status code and headers for a [`Responder`].
 ///
@@ -143,7 +145,7 @@ impl<R: Responder> CustomizeResponder<R> {
 impl<T> Responder for CustomizeResponder<T>
 where
     T: Responder,
-    <T::Body as MessageBody>::Error: Into<BoxError>,
+    <T::Body as MessageBody>::Error: fmt::Debug,
 {
     type Body = EitherBody<T::Body>;
 

src/response/responder.rs

@@ -1,4 +1,4 @@
-use std::borrow::Cow;
+use std::{borrow::Cow, fmt};
 
 use actix_http::{
     body::{BoxBody, EitherBody, MessageBody},
@@ -7,7 +7,7 @@ use actix_http::{
 };
 use bytes::{Bytes, BytesMut};
 
-use crate::{BoxError, Error, HttpRequest, HttpResponse, HttpResponseBuilder};
+use crate::{Error, HttpRequest, HttpResponse, HttpResponseBuilder};
 
 use super::CustomizeResponder;
 
@@ -96,7 +96,7 @@ impl Responder for actix_http::ResponseBuilder {
 impl<T> Responder for Option<T>
 where
     T: Responder,
-    <T::Body as MessageBody>::Error: Into<BoxError>,
+    <T::Body as MessageBody>::Error: fmt::Debug,
 {
     type Body = EitherBody<T::Body>;
 
@@ -111,7 +111,7 @@ where
 impl<T, E> Responder for Result<T, E>
 where
     T: Responder,
-    <T::Body as MessageBody>::Error: Into<BoxError>,
+    <T::Body as MessageBody>::Error: fmt::Debug,
     E: Into<Error>,
 {
     type Body = EitherBody<T::Body>;

src/route.rs

@@ -1,4 +1,4 @@
-use std::{future::Future, mem, rc::Rc};
+use std::{fmt, future::Future, mem, rc::Rc};
 
 use actix_http::Method;
 use actix_service::{
@@ -12,7 +12,7 @@ use crate::{
     guard::{self, Guard},
     handler::{handler_service, Handler},
     service::{BoxedHttpServiceFactory, ServiceRequest, ServiceResponse},
-    BoxError, Error, FromRequest, HttpResponse, Responder,
+    Error, FromRequest, HttpResponse, Responder,
 };
 
 /// Resource route definition
@@ -183,7 +183,7 @@ impl Route {
         R: Future + 'static,
         R::Output: Responder + 'static,
         <R::Output as Responder>::Body: MessageBody,
-        <<R::Output as Responder>::Body as MessageBody>::Error: Into<BoxError>,
+        <<R::Output as Responder>::Body as MessageBody>::Error: fmt::Debug,
     {
         self.service = handler_service(handler);
         self

src/service.rs

@@ -470,7 +470,6 @@ impl<B> From<ServiceResponse<B>> for Response<B> {
 impl<B> fmt::Debug for ServiceResponse<B>
 where
     B: MessageBody,
-    B::Error: Into<Error>,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let res = writeln!(

src/web.rs

@@ -1,6 +1,6 @@
 //! Essentials helper functions and types for application registration.
 
-use std::{error::Error as StdError, future::Future};
+use std::{fmt, future::Future};
 
 use actix_http::Method;
 use actix_router::IntoPatterns;
@@ -146,7 +146,7 @@ where
     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>>,
+    <<R::Output as Responder>::Body as MessageBody>::Error: fmt::Debug,
 {
     Route::new().to(handler)
 }