I'm officer in hanyang university.
when some users access the main page, sometime they see error message screen(refere to attachment file)
so they gotta click the refresh button.
The error is a java.lang.NullPointerException that is being caused by the custom login page that is being used.
I have confirmed that the custom login page is causing the error by downloading it and apply it to an internal test instance. When I did this the same issue occurred when I received an Error on first access and then it worked on reloading.