--- a/src/http/ngx_http_file_cache.c
+++ b/src/http/ngx_http_file_cache.c
@@ -338,7 +338,7 @@ ngx_http_file_cache_read(ngx_http_reques
         return n;
     }
 
-    if ((size_t) n <= c->header_start) {
+    if ((size_t) n < c->header_start) {
         ngx_log_error(NGX_LOG_CRIT, r->connection->log, 0,
                       "cache file \"%s\" is too small", c->file.name.data);
         return NGX_ERROR;

--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -752,6 +752,11 @@ ngx_http_upstream_cache_send(ngx_http_re
     r->cached = 1;
     c = r->cache;
 
+    if (c->header_start == c->body_start) {
+        r->http_version = NGX_HTTP_VERSION_9;
+        return ngx_http_cache_send(r);
+    }
+
     /* TODO: cache stack */
 
     u->buffer = *c->buf;