TYPO3 Core

If no Backend session exists I get this PHP error:

PHP Fatal error: Call to undefined method stdClass::isAdminPanelVisible() in /var/www/.../typo3/sysext/cms/tslib/index_ts.php on line 578

Line 578 in Version 4.5.x
Line 506 in Version 4.6.x
Line 474 in Version 4.7.x

The affected code looks like this:

if (is_object($BE_USER) && $BE_USER->isAdminPanelVisible() && $TSFE->beUserLogin) {
    $TSFE->content = str_ireplace('</head>',  $BE_USER->adminPanel->getAdminPanelHeaderData() . '</head>', $TSFE->content);
    $TSFE->content = str_ireplace('</body>',  $BE_USER->displayAdminPanel() . '</body>', $TSFE->content);
}

This is my patch after each TYPO3 Update:

if (is_object($BE_USER) && method_exists($BE_USER, 'isAdminPanelVisible')) {
    if($BE_USER->isAdminPanelVisible() && $TSFE->beUserLogin) {
        $TSFE->content = str_ireplace('</head>',  $BE_USER->adminPanel->getAdminPanelHeaderData() . '</head>', $TSFE->content);
        $TSFE->content = str_ireplace('</body>',  $BE_USER->displayAdminPanel() . '</body>', $TSFE->content);
    }
}

Only one of my 80 installations on the same server is affected and I could not find the reason why only this installation is affected.