Can't edit/create an exhibit

Seong_Lee / 2019-02-19 03:40:35   

Hi, I'm working on my website seonghaklee.com

but at some point, it dose not let me edit. when I click edit,

the page chages to "This page isn’t working seonghaklee.com is currently unable to handle this request.
HTTP ERROR 500" Page.

could anybody help me on this?

thank you