php代码没有在php 5.5 wordpress 4.8中执行while while（）循环

Question

这是与wordpress插件的DB升级相关的功能 'do'中的代码没有被执行。 此文件用于在插件表中进行更改。 有人可以帮我解决这个问题吗？

php版本是 - 5.5，wordpress - 4.8

 public function upgrade($version)
 {
    @set_time_limit(300);

    if ($version === false || ((int)$version) > WpProQuiz_Helper_DbUpgrade::WPPROQUIZ_DB_VERSION) {
        $this->install();

        return WpProQuiz_Helper_DbUpgrade::WPPROQUIZ_DB_VERSION;
    }

    $version = (int)$version;

    if ($version === WpProQuiz_Helper_DbUpgrade::WPPROQUIZ_DB_VERSION) {
        return WpProQuiz_Helper_DbUpgrade::WPPROQUIZ_DB_VERSION;
    }

    do {
        $f = 'upgradeDbV' . $version;

        if (method_exists($this, $f)) {
            $version = $this->$f();
        } else {
            die("WpProQuiz upgrade error");
        }
    } while ($version < WpProQuiz_Helper_DbUpgrade::WPPROQUIZ_DB_VERSION);

    return WpProQuiz_Helper_DbUpgrade::WPPROQUIZ_DB_VERSION;
}