解決了,將 php 版本升到 7.2 以上就沒有問題了。
這是官方中文推薦的版本要求:
服務器環境要求
PHP 5.2.4 或更新版本
MySQL 5.0 或更新版本
Apache mod_rewrite 模塊 (可選,用於支持 「固定鏈接」 和 「站點網絡」 功能)
這是英文官方給的版本要求:
Requirements
To run WordPress we recommend your host supports:
PHP version 7.2 or greater.
MySQL version 5.6 or greater OR MariaDB version 10.0 or greater.
HTTPS support
If you are in a legacy environment where you only have older PHP or MySQL versions, WordPress also works with PHP 5.2.4+ and MySQL 5.0+, but these versions have reached official End Of Life and as such may expose your site to security vulnerabilities.