Redirects & can not access to backend

Hello,

I tested it in Multisites of wordpress 4.8.3, with twenty-seven, twenty-six theme, there is no any other plugins.

once it was activated, it will show the error message, and any access to backend will be redirect to URL http://subsite.ourdomain.com/wp-admin/admin.php?page=anspress_about:

http://prntscr.com/hby0ak

Anyway to resolve?

Alex