diff --git a/src/event/ngx_event_pipe.c b/src/event/ngx_event_pipe.c
index 7bbca4b24c..c3ac400434 100644
--- a/src/event/ngx_event_pipe.c
+++ b/src/event/ngx_event_pipe.c
@@ -539,6 +539,21 @@ ngx_event_pipe_write_to_downstream(ngx_event_pipe_t *p)
 
         if (p->upstream_eof || p->upstream_error || p->upstream_done) {
 
+            /* the first free buf is partially filled */
+
+            if (p->upstream_error
+                && p->free_raw_bufs
+                && p->free_raw_bufs->buf->pos != p->free_raw_bufs->buf->last)
+            {
+                /* STUB */ p->free_raw_bufs->buf->num = p->num++;
+
+                if (p->input_filter(p, p->free_raw_bufs->buf) == NGX_ERROR) {
+                    return NGX_ABORT;
+                }
+
+                p->free_raw_bufs = p->free_raw_bufs->next;
+            }
+
             /* pass the p->out and p->in chains to the output filter */
 
             for (cl = p->busy; cl; cl = cl->next) {
diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 3f865345ba..918aa239cf 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -4369,6 +4369,19 @@ ngx_http_upstream_process_upstream(ngx_http_request_t *r,
         p->upstream_error = 1;
         ngx_connection_error(c, NGX_ETIMEDOUT, "upstream timed out");
 
+        /*
+         * flush data already read from the upstream, except for
+         * an unrequested 101 response, whose body is not part
+         * of the response
+         */
+
+        if (u->headers_in.status_n != NGX_HTTP_SWITCHING_PROTOCOLS
+            && ngx_event_pipe(p, 1) == NGX_ABORT)
+        {
+            ngx_http_upstream_finalize_request(r, u, NGX_ERROR);
+            return;
+        }
+
     } else {
 
         if (rev->delayed) {