diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index 3b36f4a19..d8ff53bfe 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -1973,6 +1973,10 @@ ngx_http_send_response(ngx_http_request_t *r, ngx_uint_t status,
 ngx_int_t
 ngx_http_send_header(ngx_http_request_t *r)
 {
+    if (r->post_action) {
+        return NGX_OK;
+    }
+
     if (r->header_sent) {
         ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
                       "header already sent");