Error 500

Hello,

When I activate the plugin, I create a new language (english).
But, when I go to my homepage (static page), there is an internal error 500.

Indeed, the URl is now http://www.mydomain.com/en and before it was http://www.mydomain.com.

I think I have to put somewhere that english is the default language but I don’t know where.

COuld you hel me please ?

https://ww.wp.xz.cn/plugins/polylang/