Emergency: fatal error on "Call to undefined function bp_is_page() "

Help! All of a sudden today I get this error on all pages:

Fatal error: Call to undefined function bp_is_page() in /public_html/wp-content/themes/bp-social/functions.php on line 577

I have not updated the site in a few weeks and it was fine until I noticed the error today. What should I do to fix it?

I can't access /wp-admin/ either, so the backend is offline to me too :slight_frown:

Thank you!