While running update.php (1.16 -> 1.19 release) I received this particular warning many times (between the messages "populateCategory.php" and "Category population complete"):
Warning: Illegal string offset 'LIMIT' in /var/www/public_html_NEW/includes/db/Database.php on line 1443
PHP 5.4.2, MediaWiki 1.19 (release).
Version: 1.19.0
Severity: minor
OS: Linux