FYI for those who upgrade to VB 4.2.5 and PHP 7.x this mod was causing a fatal error in the init_startup plugin which means you can't get to the admincp or the forum. You can either do the edits below before upgrading to PHP7, or add the disable hooks line to your config.php file to get access back if you already updated:
PHP Code:
define("DISABLE_HOOKS",true);
In Plugin Manager edit the Explain plugin (on hook init)startup) as follows.
Find the line:
PHP Code:
$newdb =& new vB_Database_Explain($vbulletin);
and comment it out - which means change it to:
PHP Code:
//$newdb =& new vB_Database_Explain($vbulletin);
Then find the line:
PHP Code:
$newdb =& new vB_Database_MySQLi_Explain($vbulletin);
and change it to:
PHP Code:
$newdb = new vB_Database_MySQLi_Explain($vbulletin);
That should fix the error.
If you added the disable hooks line to config.php you can now remove it or comment it out.