Call to undefined function _wp_get_user_contactmethods() error when using accountform shortcode

Hi,

When I try to add the [accountform] shortcode on a page the form does not render and I get the following error:

Fatal error: Call to undefined function _wp_get_user_contactmethods() in /(wordpress directory)/wp-admin/includes/user.php on line 382

Everything else appears to be working. The only plugins I have active are BackupBuddy, Category pagination fix, and Membership Premium. What could be causing this error?

Thanks.