diff --git a/lib/includes/nghttp2/nghttp2.h b/lib/includes/nghttp2/nghttp2.h
index 8af4d2a7..a19a5112 100644
--- a/lib/includes/nghttp2/nghttp2.h
+++ b/lib/includes/nghttp2/nghttp2.h
@@ -454,11 +454,7 @@ typedef enum {
   /**
    * The ALTSVC extension frame.
    */
-  NGHTTP2_EXT_ALTSVC = 0x0a,
-  /**
-   * The BLOCKED extension frame.
-   */
-  NGHTTP2_EXT_BLOCKED = 0x0b
+  NGHTTP2_EXT_ALTSVC = 0x0a
 } nghttp2_ext_frame_type;
 
 /**
@@ -962,9 +958,6 @@ typedef struct {
    *
    * If hd.type == :enum:`NGHTTP2_EXT_ALTSVC`, it is a pointer to
    * :type:`nghttp2_ext_altsvc`.
-   *
-   * If hd.type == :enum:`NGHTTP2_EXT_BLOCKED`, it points to ``NULL``,
-   * since BLOCKED extension frame has no payload.
    */
   void *payload;
 } nghttp2_extension;
diff --git a/lib/nghttp2_frame.c b/lib/nghttp2_frame.c
index f8f73861..c48ba3e8 100644
--- a/lib/nghttp2_frame.c
+++ b/lib/nghttp2_frame.c
@@ -227,15 +227,6 @@ void nghttp2_frame_altsvc_free(nghttp2_extension *frame)
   free(altsvc->protocol_id);
 }
 
-void nghttp2_frame_blocked_init(nghttp2_extension *frame, int32_t stream_id)
-{
-  frame_set_hd(&frame->hd, 0, NGHTTP2_EXT_BLOCKED, NGHTTP2_FLAG_NONE,
-               stream_id);
-}
-
-void nghttp2_frame_blocked_free(nghttp2_extension *frame)
-{}
-
 void nghttp2_frame_data_init(nghttp2_data *frame, nghttp2_private_data *pdata)
 {
   frame->hd = pdata->hd;
@@ -892,20 +883,6 @@ int nghttp2_frame_unpack_altsvc_payload(nghttp2_extension *frame,
   return 0;
 }
 
-int nghttp2_frame_pack_blocked(nghttp2_bufs *bufs, nghttp2_extension *frame)
-{
-  nghttp2_buf *buf;
-
-  assert(bufs->head == bufs->cur);
-
-  buf = &bufs->head->buf;
-  buf->pos -= NGHTTP2_FRAME_HDLEN;
-
-  nghttp2_frame_pack_frame_hd(buf->pos, &frame->hd);
-
-  return 0;
-}
-
 nghttp2_settings_entry* nghttp2_frame_iv_copy(const nghttp2_settings_entry *iv,
                                               size_t niv)
 {
diff --git a/lib/nghttp2_frame.h b/lib/nghttp2_frame.h
index c398ceb3..950e6086 100644
--- a/lib/nghttp2_frame.h
+++ b/lib/nghttp2_frame.h
@@ -443,16 +443,6 @@ int nghttp2_frame_unpack_altsvc_payload(nghttp2_extension *frame,
                                         uint8_t *var_gift_payload,
                                         size_t var_gift_payloadlen);
 
-/*
- * Packs BLOCKED frame |frame| in wire format and store it in |bufs|.
- *
- * The caller must make sure that nghttp2_bufs_reset(bufs) is called
- * before calling this function.
- *
- * This function always returns 0.
- */
-int nghttp2_frame_pack_blocked(nghttp2_bufs *bufs, nghttp2_extension *frame);
-
 /*
  * Initializes HEADERS frame |frame| with given values.  |frame| takes
  * ownership of |nva|, so caller must not free it. If |stream_id| is
@@ -548,10 +538,6 @@ void nghttp2_frame_altsvc_init(nghttp2_extension *frame, int32_t stream_id,
  */
 void nghttp2_frame_altsvc_free(nghttp2_extension *frame);
 
-void nghttp2_frame_blocked_init(nghttp2_extension *frame, int32_t stream_id);
-
-void nghttp2_frame_blocked_free(nghttp2_extension *frame);
-
 void nghttp2_frame_data_init(nghttp2_data *frame, nghttp2_private_data *pdata);
 
 /*
diff --git a/lib/nghttp2_session.c b/lib/nghttp2_session.c
index afc2b275..ab280458 100644
--- a/lib/nghttp2_session.c
+++ b/lib/nghttp2_session.c
@@ -240,9 +240,6 @@ static void session_inbound_frame_reset(nghttp2_session *session)
   case NGHTTP2_EXT_ALTSVC:
     nghttp2_frame_altsvc_free(&iframe->frame.ext);
     break;
-  case NGHTTP2_EXT_BLOCKED:
-    nghttp2_frame_blocked_free(&iframe->frame.ext);
-    break;
   }
 
   memset(&iframe->frame, 0, sizeof(nghttp2_frame));
@@ -1291,41 +1288,6 @@ static int session_predicate_altsvc_send
   return 0;
 }
 
-/*
- * This function checks BLOCKED with the stream ID |stream_id| can be
- * sent at this time.  If |stream_id| is 0, BLOCKED frame is always
- * allowed to send.
- *
- * This function returns 0 if it succeeds, or one of the following
- * negative error codes:
- *
- * NGHTTP2_ERR_STREAM_CLOSED
- *     The stream is already closed or does not exist.
- * NGHTTP2_ERR_STREAM_CLOSING
- *     RST_STREAM was queued for this stream.
- */
-static int session_predicate_blocked_send
-(nghttp2_session *session, int32_t stream_id)
-{
-  nghttp2_stream *stream;
-
-  if(stream_id == 0) {
-    return 0;
-  }
-
-  stream = nghttp2_session_get_stream(session, stream_id);
-
-  if(stream == NULL) {
-    return NGHTTP2_ERR_STREAM_CLOSED;
-  }
-
-  if(stream->state == NGHTTP2_STREAM_CLOSING) {
-    return NGHTTP2_ERR_STREAM_CLOSING;
-  }
-
-  return 0;
-}
-
 /*
  * This function checks SETTINGS can be sent at this time.
  *
@@ -1480,71 +1442,6 @@ static int session_headers_add_pad(nghttp2_session *session,
   return 0;
 }
 
-/*
- * Adds BLOCKED frame to outbound queue.  The |stream_id| could be 0,
- * which means DATA is blocked by connection level flow control.
- *
- * This function returns 0 if it succeeds, or one of the following
- * negative error codes:
- *
- * NGHTTP2_ERR_NOMEM
- *     Out of memory
- */
-static int session_add_blocked(nghttp2_session *session, int32_t stream_id)
-{
-  int rv;
-  nghttp2_frame *frame;
-
-  frame = malloc(sizeof(nghttp2_frame));
-
-  if(frame == NULL) {
-    return NGHTTP2_ERR_NOMEM;
-  }
-
-  frame->ext.payload = NULL;
-
-  nghttp2_frame_blocked_init(&frame->ext, stream_id);
-
-  rv = nghttp2_session_add_frame(session, NGHTTP2_CAT_CTRL, frame, NULL);
-
-  if(rv != 0) {
-    nghttp2_frame_blocked_free(&frame->ext);
-    free(frame);
-
-    return rv;
-  }
-  return 0;
-}
-
-/*
- * Adds BLOCKED frame(s) to outbound queue if they are allowed to
- * send.  We check BLOCKED frame can be sent for connection and stream
- * individually.
- *
- * This function returns 0 if it succeeds, or one of the following
- * negative error codes:
- *
- * NGHTTP2_ERR_NOMEM
- *     Out of memory
- */
-static int session_consider_blocked(nghttp2_session *session,
-                                    nghttp2_stream *stream)
-{
-  if(session->blocked_sent == 0 && session->remote_window_size <= 0) {
-    session->blocked_sent = 1;
-
-    return session_add_blocked(session, 0);
-  }
-
-  if(stream->blocked_sent == 0 && stream->remote_window_size <= 0) {
-    stream->blocked_sent = 1;
-
-    return session_add_blocked(session, stream->stream_id);
-  }
-
-  return 0;
-}
-
 /*
  * This function serializes frame for transmission.
  *
@@ -1762,20 +1659,6 @@ static int session_prep_frame(nghttp2_session *session,
         return framerv;
       }
 
-      break;
-    case NGHTTP2_EXT_BLOCKED:
-      rv = session_predicate_blocked_send(session, frame->hd.stream_id);
-      if(rv != 0) {
-        return rv;
-      }
-
-      framerv = nghttp2_frame_pack_blocked(&session->aob.framebufs,
-                                           &frame->ext);
-
-      if(framerv < 0) {
-        return framerv;
-      }
-
       break;
     default:
       return NGHTTP2_ERR_INVALID_ARGUMENT;
@@ -1813,12 +1696,6 @@ static int session_prep_frame(nghttp2_session *session,
     next_readmax = nghttp2_session_next_data_read(session, stream);
 
     if(next_readmax == 0) {
-      rv = session_consider_blocked(session, stream);
-
-      if(nghttp2_is_fatal(rv)) {
-        return rv;
-      }
-
       rv = nghttp2_stream_defer_data(stream,
                                      NGHTTP2_STREAM_FLAG_DEFERRED_FLOW_CONTROL,
                                      &session->ob_pq, session->last_cycle);
@@ -2227,12 +2104,6 @@ static int session_after_frame_sent(nghttp2_session *session)
       next_readmax = nghttp2_session_next_data_read(session, stream);
 
       if(next_readmax == 0) {
-        rv = session_consider_blocked(session, stream);
-
-        if(nghttp2_is_fatal(rv)) {
-          return rv;
-        }
-
         rv = nghttp2_stream_defer_data
           (stream, NGHTTP2_STREAM_FLAG_DEFERRED_FLOW_CONTROL, &session->ob_pq,
            session->last_cycle);
@@ -3177,10 +3048,6 @@ static int update_remote_initial_window_size_func
                                              NGHTTP2_FLOW_CONTROL_ERROR);
   }
 
-  if(stream->remote_window_size > 0) {
-    stream->blocked_sent = 0;
-  }
-
   /* If window size gets positive, push deferred DATA frame to
      outbound queue. */
   if(nghttp2_stream_check_deferred_by_flow_control(stream) &&
@@ -3725,22 +3592,6 @@ static int session_process_altsvc_frame(nghttp2_session *session)
   return nghttp2_session_on_altsvc_received(session, frame);
 }
 
-int nghttp2_session_on_blocked_received(nghttp2_session *session,
-                                        nghttp2_frame *frame)
-{
-  return session_call_on_frame_received(session, frame);
-}
-
-static int session_process_blocked_frame(nghttp2_session *session)
-{
-  nghttp2_inbound_frame *iframe = &session->iframe;
-  nghttp2_frame *frame = &iframe->frame;
-
-  frame->ext.payload = NULL;
-
-  return nghttp2_session_on_blocked_received(session, frame);
-}
-
 static int push_back_deferred_data_func(nghttp2_map_entry *entry, void *ptr)
 {
   int rv;
@@ -3789,7 +3640,6 @@ static int session_on_connection_window_update_received
   /* To queue the DATA deferred by connection-level flow-control, we
      have to check all streams. Bad. */
   if(session->remote_window_size > 0) {
-    session->blocked_sent = 0;
 
     rv = session_push_back_deferred_data(session);
     if(rv != 0) {
@@ -3825,10 +3675,6 @@ static int session_on_stream_window_update_received
   }
   stream->remote_window_size += frame->window_update.window_size_increment;
 
-  if(stream->remote_window_size > 0) {
-    stream->blocked_sent = 0;
-  }
-
   if(stream->remote_window_size > 0 &&
      session->remote_window_size > 0 &&
      nghttp2_stream_check_deferred_by_flow_control(stream)) {
@@ -4552,27 +4398,6 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
         iframe->state = NGHTTP2_IB_READ_NBYTE;
         inbound_frame_set_mark(iframe, NGHTTP2_ALTSVC_FIXED_PARTLEN);
 
-        break;
-      case NGHTTP2_EXT_BLOCKED:
-        DEBUGF(fprintf(stderr, "recv: BLOCKED\n"));
-
-        iframe->frame.hd.flags = NGHTTP2_FLAG_NONE;
-
-        if(iframe->payloadleft != 0) {
-          busy = 1;
-
-          iframe->state = NGHTTP2_IB_FRAME_SIZE_ERROR;
-
-          break;
-        }
-
-        rv = session_process_blocked_frame(session);
-        if(nghttp2_is_fatal(rv)) {
-          return rv;
-        }
-
-        session_inbound_frame_reset(session);
-
         break;
       default:
         DEBUGF(fprintf(stderr, "recv: unknown frame\n"));
diff --git a/lib/nghttp2_session.h b/lib/nghttp2_session.h
index 6d6787b0..5ba7af5a 100644
--- a/lib/nghttp2_session.h
+++ b/lib/nghttp2_session.h
@@ -223,9 +223,6 @@ struct nghttp2_session {
   /* Flags indicating GOAWAY is sent and/or recieved. The flags are
      composed by bitwise OR-ing nghttp2_goaway_flag. */
   uint8_t goaway_flags;
-  /* nonzero if blocked was sent and remote_window_size is still 0 or
-     negative */
-  uint8_t blocked_sent;
 };
 
 /* Struct used when updating initial window size of each active
@@ -600,19 +597,6 @@ int nghttp2_session_on_window_update_received(nghttp2_session *session,
 int nghttp2_session_on_altsvc_received(nghttp2_session *session,
                                        nghttp2_frame *frame);
 
-/*
- * Called when BLOCKED is received, assuming |frame| is properly
- * initialized.
- *
- * This function returns 0 if it succeeds, or one of the following
- * negative error codes:
- *
- * NGHTTP2_ERR_CALLBACK_FAILURE
- *   The callback function failed.
- */
-int nghttp2_session_on_blocked_received(nghttp2_session *session,
-                                        nghttp2_frame *frame);
-
 /*
  * Called when DATA is received, assuming |frame| is properly
  * initialized.
diff --git a/src/app_helper.cc b/src/app_helper.cc
index 98c84ca0..336fa013 100644
--- a/src/app_helper.cc
+++ b/src/app_helper.cc
@@ -129,8 +129,6 @@ const char* strframetype(uint8_t type)
     return "WINDOW_UPDATE";
   case NGHTTP2_EXT_ALTSVC:
     return "ALTSVC";
-  case NGHTTP2_EXT_BLOCKED:
-    return "BLOCKED";
   default:
     return "UNKNOWN";
   }