replace existing file manager - appears obsolete and not supported +6 years since any activity
replace with the simple tinyfilemanager.php script by https://tinyfilemanager.github.io/ (Maikuolan)
TinyFileManager is web based PHP file manager and it is a simple, fast and small size in single-file PHP file that can be dropped into any folder on your server, multi-language ready web application for storing, uploading, editing and managing files and folders online via web browser. The Application runs on PHP 5.5+, It allows the creation of multiple users and each user can have its own directory and a build-in support for managing text files with cloud9 IDE and it supports syntax highlighting for over 150+ languages and over 35+ themes.
Demo
https://tinyfilemanager.github.io/demo/