nginx 0.7.27 *) Feature: the "try_files" directive. *) Feature: variables support in the "fastcgi_pass" directive. *) Feature: now the $geo variable may get an address from a variable. Thanks to Andrei Nigmatulin. *) Feature: now a location's modifier may be used without space before name. *) Feature: the $upstream_response_length variable. *) Bugfix: now a "add_header" directive does not add an empty value. *) Bugfix: if zero length static file was requested, then nginx just closed connection; the bug had appeared in 0.7.25. *) Bugfix: a MOVE method could not move file in non-existent directory. *) Bugfix: a segmentation fault occurred in worker process, if no one named location was defined in server, but some one was used in an error_page directive. Thanks to Sergey Bochenkov.

--- a/src/http/modules/ngx_http_headers_filter_module.c
+++ b/src/http/modules/ngx_http_headers_filter_module.c
@@ -325,15 +325,17 @@ ngx_http_add_header(ngx_http_request_t *
 {
     ngx_table_elt_t  *h;
 
-    h = ngx_list_push(&r->headers_out.headers);
-    if (h == NULL) {
-        return NGX_ERROR;
+    if (value->len) {
+        h = ngx_list_push(&r->headers_out.headers);
+        if (h == NULL) {
+            return NGX_ERROR;
+        }
+
+        h->hash = hv->value.hash;
+        h->key = hv->value.key;
+        h->value = *value;
     }
 
-    h->hash = hv->value.hash;
-    h->key = hv->value.key;
-    h->value = *value;
-
     return NGX_OK;
 }