diff --git a/src/HttpServer.cc b/src/HttpServer.cc
index d3e5c55c..862de3c8 100644
--- a/src/HttpServer.cc
+++ b/src/HttpServer.cc
@@ -247,8 +247,7 @@ private:
 };
 
 Stream::Stream(Http2Handler *handler, int32_t stream_id)
-    : handler(handler), body_left(0), upload_left(-1), stream_id(stream_id),
-      file(-1) {
+    : handler(handler), body_left(0), stream_id(stream_id), file(-1) {
   auto config = handler->get_config();
   ev_timer_init(&rtimer, stream_timeout_cb, 0., config->stream_read_timeout);
   ev_timer_init(&wtimer, stream_timeout_cb, 0., config->stream_write_timeout);
@@ -1021,44 +1020,8 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
     return 0;
   }
 
-  if (!http2::check_nv(name, namelen, value, valuelen)) {
-    hd->submit_rst_stream(stream, NGHTTP2_PROTOCOL_ERROR);
-    return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-  }
-
   auto token = http2::lookup_token(name, namelen);
 
-  if (name[0] == ':') {
-    if ((!stream->headers.empty() &&
-         stream->headers.back().name.c_str()[0] != ':') ||
-        !http2::check_http2_request_pseudo_header(stream->hdidx, token)) {
-
-      hd->submit_rst_stream(stream, NGHTTP2_PROTOCOL_ERROR);
-      return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-    }
-  }
-
-  if (!http2::http2_header_allowed(token)) {
-    hd->submit_rst_stream(stream, NGHTTP2_PROTOCOL_ERROR);
-    return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-  }
-
-  switch (token) {
-  case http2::HD_CONTENT_LENGTH: {
-    auto upload_left = util::parse_uint(value, valuelen);
-    if (upload_left != -1) {
-      stream->upload_left = upload_left;
-    }
-    break;
-  }
-  case http2::HD_TE:
-    if (!util::strieq("trailers", value, valuelen)) {
-      hd->submit_rst_stream(stream, NGHTTP2_PROTOCOL_ERROR);
-      return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-    }
-    break;
-  }
-
   http2::index_header(stream->hdidx, token, stream->headers.size());
   http2::add_header(stream->headers, name, namelen, value, valuelen,
                     flags & NGHTTP2_NV_FLAG_NO_INDEX, token);
@@ -1104,10 +1067,6 @@ int hd_on_frame_recv_callback(nghttp2_session *session,
 
     if (frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
       remove_stream_read_timeout(stream);
-      if (stream->upload_left > 0) {
-        hd->submit_rst_stream(stream, NGHTTP2_PROTOCOL_ERROR);
-        return 0;
-      }
       if (!hd->get_config()->early_response) {
         prepare_response(stream, hd);
       }
@@ -1125,11 +1084,6 @@ int hd_on_frame_recv_callback(nghttp2_session *session,
 
     if (frame->headers.cat == NGHTTP2_HCAT_REQUEST) {
 
-      if (!http2::http2_mandatory_request_headers_presence(stream->hdidx)) {
-        hd->submit_rst_stream(stream, NGHTTP2_PROTOCOL_ERROR);
-        return 0;
-      }
-
       auto expect100 =
           http2::get_header(stream->hdidx, http2::HD_EXPECT, stream->headers);
 
@@ -1144,10 +1098,6 @@ int hd_on_frame_recv_callback(nghttp2_session *session,
 
     if (frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
       remove_stream_read_timeout(stream);
-      if (stream->upload_left > 0) {
-        hd->submit_rst_stream(stream, NGHTTP2_PROTOCOL_ERROR);
-        return 0;
-      }
       if (!hd->get_config()->early_response) {
         prepare_response(stream, hd);
       }
@@ -1244,15 +1194,6 @@ int on_data_chunk_recv_callback(nghttp2_session *session, uint8_t flags,
 
   // TODO Handle POST
 
-  if (stream->upload_left != -1) {
-    if (stream->upload_left < static_cast<int64_t>(len)) {
-      stream->upload_left = -1;
-      hd->submit_rst_stream(stream, NGHTTP2_PROTOCOL_ERROR);
-      return 0;
-    }
-    stream->upload_left -= len;
-  }
-
   add_stream_read_timeout(stream);
 
   return 0;
diff --git a/src/HttpServer.h b/src/HttpServer.h
index 222daeb7..54b7abaf 100644
--- a/src/HttpServer.h
+++ b/src/HttpServer.h
@@ -81,7 +81,6 @@ struct Stream {
   ev_timer rtimer;
   ev_timer wtimer;
   int64_t body_left;
-  int64_t upload_left;
   int32_t stream_id;
   int file;
   http2::HeaderIndex hdidx;
diff --git a/src/nghttp.cc b/src/nghttp.cc
index 986bf59c..dcc69b52 100644
--- a/src/nghttp.cc
+++ b/src/nghttp.cc
@@ -1505,12 +1505,6 @@ int on_data_chunk_recv_callback(nghttp2_session *session, uint8_t flags,
                                         user_data);
   }
 
-  if (req->expect_final_response) {
-    nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE, stream_id,
-                              NGHTTP2_PROTOCOL_ERROR);
-    return 0;
-  }
-
   req->response_len += len;
 
   if (req->inflater) {
@@ -1667,12 +1661,6 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
                                flags, user_data);
   }
 
-  if (!http2::check_nv(name, namelen, value, valuelen)) {
-    nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE, frame->hd.stream_id,
-                              NGHTTP2_PROTOCOL_ERROR);
-    return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-  }
-
   switch (frame->hd.type) {
   case NGHTTP2_HEADERS: {
     auto req = static_cast<Request *>(
@@ -1682,23 +1670,14 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
       break;
     }
 
-    if (frame->headers.cat != NGHTTP2_HCAT_RESPONSE &&
-        frame->headers.cat != NGHTTP2_HCAT_PUSH_RESPONSE &&
-        (frame->headers.cat != NGHTTP2_HCAT_HEADERS ||
-         !req->expect_final_response)) {
+    /* ignore trailer header */
+    if (frame->headers.cat == NGHTTP2_HCAT_HEADERS &&
+        !req->expect_final_response) {
       break;
     }
 
     auto token = http2::lookup_token(name, namelen);
 
-    if (name[0] == ':') {
-      if (!req->response_pseudo_header_allowed(token)) {
-        nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE,
-                                  frame->hd.stream_id, NGHTTP2_PROTOCOL_ERROR);
-        return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-      }
-    }
-
     http2::index_header(req->res_hdidx, token, req->res_nva.size());
     http2::add_header(req->res_nva, name, namelen, value, valuelen,
                       flags & NGHTTP2_NV_FLAG_NO_INDEX, token);
@@ -1714,15 +1693,6 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
 
     auto token = http2::lookup_token(name, namelen);
 
-    if (name[0] == ':') {
-      if (!req->push_request_pseudo_header_allowed(token)) {
-        nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE,
-                                  frame->push_promise.promised_stream_id,
-                                  NGHTTP2_PROTOCOL_ERROR);
-        break;
-      }
-    }
-
     http2::index_header(req->req_hdidx, token, req->req_nva.size());
     http2::add_header(req->req_nva, name, namelen, value, valuelen,
                       flags & NGHTTP2_NV_FLAG_NO_INDEX, token);
@@ -1752,12 +1722,6 @@ int on_frame_recv_callback2(nghttp2_session *session,
       ;
     }
 
-    if (req->expect_final_response) {
-      nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE, frame->hd.stream_id,
-                                NGHTTP2_PROTOCOL_ERROR);
-      return 0;
-    }
-
     if (frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
       req->record_response_end_time();
     }
@@ -1795,11 +1759,6 @@ int on_frame_recv_callback2(nghttp2_session *session,
     }
 
     if (frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
-      if (req->expect_final_response) {
-        nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE,
-                                  frame->hd.stream_id, NGHTTP2_PROTOCOL_ERROR);
-        return 0;
-      }
       req->record_response_end_time();
     }
 
@@ -1826,9 +1785,7 @@ int on_frame_recv_callback2(nghttp2_session *session,
       authority = req->get_req_header(http2::HD_HOST);
     }
 
-    if (!scheme || !authority || !method || !path || scheme->value.empty() ||
-        authority->value.empty() || method->value.empty() ||
-        path->value.empty() || path->value[0] != '/') {
+    if (!scheme || !authority || !method || !path || path->value[0] != '/') {
       nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE,
                                 frame->push_promise.promised_stream_id,
                                 NGHTTP2_PROTOCOL_ERROR);
diff --git a/src/shrpx_http2_session.cc b/src/shrpx_http2_session.cc
index f0af34b2..2d08e7f6 100644
--- a/src/shrpx_http2_session.cc
+++ b/src/shrpx_http2_session.cc
@@ -692,7 +692,6 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
                        const uint8_t *name, size_t namelen,
                        const uint8_t *value, size_t valuelen, uint8_t flags,
                        void *user_data) {
-  auto http2session = static_cast<Http2Session *>(user_data);
   auto sd = static_cast<StreamData *>(
       nghttp2_session_get_stream_user_data(session, frame->hd.stream_id));
   if (!sd || !sd->dconn) {
@@ -716,40 +715,12 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
     }
     return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
   }
-  if (!http2::check_nv(name, namelen, value, valuelen)) {
-    return 0;
-  }
 
   auto token = http2::lookup_token(name, namelen);
 
-  if (name[0] == ':') {
-    if (!downstream->response_pseudo_header_allowed(token)) {
-      http2session->submit_rst_stream(frame->hd.stream_id,
-                                      NGHTTP2_PROTOCOL_ERROR);
-      return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-    }
-  }
-
-  if (!http2::http2_header_allowed(token)) {
-    http2session->submit_rst_stream(frame->hd.stream_id,
-                                    NGHTTP2_PROTOCOL_ERROR);
-    return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-  }
-
   if (token == http2::HD_CONTENT_LENGTH) {
+    // libnghttp2 guarantees this can be parsed
     auto len = util::parse_uint(value, valuelen);
-    if (len == -1) {
-      http2session->submit_rst_stream(frame->hd.stream_id,
-                                      NGHTTP2_PROTOCOL_ERROR);
-      downstream->set_response_state(Downstream::MSG_BAD_HEADER);
-      return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-    }
-    if (downstream->get_response_content_length() != -1) {
-      http2session->submit_rst_stream(frame->hd.stream_id,
-                                      NGHTTP2_PROTOCOL_ERROR);
-      downstream->set_response_state(Downstream::MSG_BAD_HEADER);
-      return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-    }
     downstream->set_response_content_length(len);
   }
 
@@ -796,18 +767,8 @@ int on_response_headers(Http2Session *http2session, Downstream *downstream,
   downstream->set_expect_final_response(false);
 
   auto status = downstream->get_response_header(http2::HD__STATUS);
-  int status_code;
-
-  if (!http2::non_empty_value(status) ||
-      (status_code = http2::parse_http_status_code(status->value)) == -1) {
-
-    http2session->submit_rst_stream(frame->hd.stream_id,
-                                    NGHTTP2_PROTOCOL_ERROR);
-    downstream->set_response_state(Downstream::MSG_RESET);
-    call_downstream_readcb(http2session, downstream);
-
-    return 0;
-  }
+  // libnghttp2 guarantees this exists and can be parsed
+  auto status_code = http2::parse_http_status_code(status->value);
 
   downstream->set_response_http_status(status_code);
   downstream->set_response_major(2);
@@ -912,12 +873,6 @@ int on_frame_recv_callback(nghttp2_session *session, const nghttp2_frame *frame,
       break;
     }
 
-    if (downstream->get_expect_final_response()) {
-      http2session->submit_rst_stream(frame->hd.stream_id,
-                                      NGHTTP2_PROTOCOL_ERROR);
-      break;
-    }
-
     auto upstream = downstream->get_upstream();
     rv = upstream->on_downstream_body(downstream, nullptr, 0, true);
     if (rv != 0) {
@@ -977,12 +932,6 @@ int on_frame_recv_callback(nghttp2_session *session, const nghttp2_frame *frame,
     }
 
     if (frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
-      if (downstream->get_expect_final_response()) {
-        http2session->submit_rst_stream(frame->hd.stream_id,
-                                        NGHTTP2_PROTOCOL_ERROR);
-        return 0;
-      }
-
       downstream->disable_downstream_rtimer();
 
       if (downstream->get_response_state() == Downstream::HEADER_COMPLETE) {
diff --git a/src/shrpx_http2_upstream.cc b/src/shrpx_http2_upstream.cc
index 14e313e3..794beaec 100644
--- a/src/shrpx_http2_upstream.cc
+++ b/src/shrpx_http2_upstream.cc
@@ -180,49 +180,12 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
 
     return 0;
   }
-  if (!http2::check_nv(name, namelen, value, valuelen)) {
-    upstream->rst_stream(downstream, NGHTTP2_PROTOCOL_ERROR);
-    return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-  }
-
   auto token = http2::lookup_token(name, namelen);
 
-  if (name[0] == ':') {
-    if (!downstream->request_pseudo_header_allowed(token)) {
-      upstream->rst_stream(downstream, NGHTTP2_PROTOCOL_ERROR);
-      return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-    }
-  }
-
-  if (!http2::http2_header_allowed(token)) {
-    upstream->rst_stream(downstream, NGHTTP2_PROTOCOL_ERROR);
-    return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-  }
-
-  switch (token) {
-  case http2::HD_CONTENT_LENGTH: {
+  if (token == http2::HD_CONTENT_LENGTH) {
+    // libnghttp2 guarantees this can be parsed
     auto len = util::parse_uint(value, valuelen);
-    if (len == -1) {
-      if (upstream->error_reply(downstream, 400) != 0) {
-        return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-      }
-      return 0;
-    }
-    if (downstream->get_request_content_length() != -1) {
-      if (upstream->error_reply(downstream, 400) != 0) {
-        return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-      }
-      return 0;
-    }
     downstream->set_request_content_length(len);
-    break;
-  }
-  case http2::HD_TE:
-    if (!util::strieq("trailers", value, valuelen)) {
-      upstream->rst_stream(downstream, NGHTTP2_PROTOCOL_ERROR);
-      return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
-    }
-    break;
   }
 
   downstream->add_request_header(name, namelen, value, valuelen,
@@ -282,34 +245,19 @@ int on_request_headers(Http2Upstream *upstream, Downstream *downstream,
     http2::dump_nv(get_config()->http2_upstream_dump_request_header, nva);
   }
 
-  auto host = downstream->get_request_header(http2::HD_HOST);
   auto authority = downstream->get_request_header(http2::HD__AUTHORITY);
   auto path = downstream->get_request_header(http2::HD__PATH);
   auto method = downstream->get_request_header(http2::HD__METHOD);
   auto scheme = downstream->get_request_header(http2::HD__SCHEME);
 
-  bool is_connect = method && "CONNECT" == method->value;
-  bool having_host = http2::non_empty_value(host);
+  bool is_connect = "CONNECT" == method->value;
   bool having_authority = http2::non_empty_value(authority);
 
-  if (is_connect) {
-    // Here we strictly require :authority header field.
-    if (scheme || path || !having_authority) {
-
+  // presence of mandatory header fields are guaranteed by libnghttp2.
+  if (!is_connect) {
+    // For HTTP/2 proxy, :authority is required.
+    if (get_config()->http2_proxy && !having_authority) {
       upstream->rst_stream(downstream, NGHTTP2_PROTOCOL_ERROR);
-
-      return 0;
-    }
-  } else {
-    // For proxy, :authority is required. Otherwise, we can accept
-    // :authority or host for methods.
-    if (!http2::non_empty_value(method) || !http2::non_empty_value(scheme) ||
-        (get_config()->http2_proxy && !having_authority) ||
-        (!get_config()->http2_proxy && !having_authority && !having_host) ||
-        !http2::non_empty_value(path)) {
-
-      upstream->rst_stream(downstream, NGHTTP2_PROTOCOL_ERROR);
-
       return 0;
     }
   }
@@ -327,11 +275,6 @@ int on_request_headers(Http2Upstream *upstream, Downstream *downstream,
 
   downstream->set_request_state(Downstream::HEADER_COMPLETE);
   if (frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
-    if (!downstream->validate_request_bodylen()) {
-      upstream->rst_stream(downstream, NGHTTP2_PROTOCOL_ERROR);
-      return 0;
-    }
-
     downstream->disable_upstream_rtimer();
 
     downstream->set_request_state(Downstream::MSG_COMPLETE);
@@ -411,11 +354,6 @@ int on_frame_recv_callback(nghttp2_session *session, const nghttp2_frame *frame,
     if (frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
       downstream->disable_upstream_rtimer();
 
-      if (!downstream->validate_request_bodylen()) {
-        upstream->rst_stream(downstream, NGHTTP2_PROTOCOL_ERROR);
-        return 0;
-      }
-
       downstream->end_upload_data();
       downstream->set_request_state(Downstream::MSG_COMPLETE);
     }
@@ -435,11 +373,6 @@ int on_frame_recv_callback(nghttp2_session *session, const nghttp2_frame *frame,
     }
 
     if (frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
-      if (!downstream->validate_request_bodylen()) {
-        upstream->rst_stream(downstream, NGHTTP2_PROTOCOL_ERROR);
-        return 0;
-      }
-
       downstream->disable_upstream_rtimer();
 
       downstream->end_upload_data();