diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 73a5882..b3580fe 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -582,6 +582,8 @@
             if (rc == NGX_HTTP_UPSTREAM_INVALID_HEADER) {
                 rc = NGX_DECLINED;
                 r->cached = 0;
+                u->buffer.start = NULL;
+                u->cache_status = NGX_HTTP_CACHE_MISS;
             }
 
             if (ngx_http_upstream_cache_background_update(r, u) != NGX_OK) {
@@ -1059,8 +1061,16 @@
         return NGX_ERROR;
     }
 
+    if (rc == NGX_AGAIN) {
+        rc = NGX_HTTP_UPSTREAM_INVALID_HEADER;
+    }
+
     /* rc == NGX_HTTP_UPSTREAM_INVALID_HEADER */
 
+    ngx_log_error(NGX_LOG_CRIT, r->connection->log, 0,
+                  "cache file \"%s\" contains invalid header",
+                  c->file.name.data);
+
     /* TODO: delete file */
 
     return rc;