MW 1.27, HHVM 3.14.3.
Warnings in `/var/hhvm/error.log` on every request:
```
\nWarning: header() expects parameter 3 to be integer, null given in /var/www/wiki/w/includes/WebResponse.php on line 42
```
On any login:
```
\nWarning: trim() expects parameter 1 to be string, null given in /var/www/wiki/w/includes/skins/SkinTemplate.php on line 354
```
In addition, although the user is logged in, an empty page is served to him.
On any edit action:
```
\nWarning: htmlspecialchars() expects parameter 1 to be string, null given in /var/www/wiki/w/includes/EditPage.php on line 3045
```
**Update on the first error message**.Which is worse, Thisthis bug also breaks saving at least some of the pages. However, it is enough to replace
```
header( $string, $replace, $http_response_code );
```
with
```
if ($http_response_code) {
header( $string, $replace, $http_response_code );
} else {
header( $string, $replace );
}
```
in line 42 of `includes/WebResponse.php` (method `WebResponse::header( $string, $replace = true, $http_response_code = null )`) to fix it.