[nerbert]

In your list of plugins (Plugin Manager) in Plugins & Products. It goes in login.php but the file is not the problem, it's some product.

When you have an error or warning message like that it lists the line in the file and the line in the plugin that goes in the hook location at the given file line.

Warning: Invalid argument supplied for foreach() in ..../login.php(119) : eval()'d code on line 4

So check line 119 in login.php and you'll see

($hook = vBulletinHook::fetch_hook('login_failure')) ? eval($hook) : false;

So it's line 4 of some plugin in "login_failure"