이 토론 포럼을 구동하는 소프트웨어에서 예기치 못한 문제가 발생했습니다: discourse

[pfaffman (Jay Pfaffman)]

You need to look at the logs on the server as described here Upgrading from 2.9.0.beta8 broke the site, unrecoverable - #11 by Benjamin_D

That topic describes a similar problem which may or may not be related to adding the plugin.