Internal Server Error in Develeopment Mode

I have installed the Frappe/ERPNext perfectly fine using EasyInstall as Production environment.

And then I was trying to follow the tutorial of Library Management, so I switch to Developer mode,
then the server shows “Internal Server Error”.

You can find here: http://derp.globizs.com

Currently using CentOS 7, 1 GB Ram, 20GB HD.

Couldn’t find the solution for the last few days.

Anyone can help me?

@kumar library management is not updated for version 5. We will update it soon. Sorry for the trouble.