How to prevent access to wp-admin for certain user roles?

Question

I did try using the plugin Front End Users but this clashes with something as it prevents access to some front end pages. So I need to manually just set it so that anyone who isn't one of two usernames (or roles) can't access wp-admin.

Answer 1

Plugin

It's basically just a user capability check, followed by a redirect in an exit call. It then redirects to the site the request came from.

<?php
! defined( 'ABSPATH' ) AND exit;
/* Plugin Name: (#66093) »kaiser« Deny Admin-UI access for certain roles */


function wpse66093_no_admin_access()
{
    $redirect = isset( $_SERVER['HTTP_REFERER'] ) ? $_SERVER['HTTP_REFERER'] : home_url( '/' );
    if ( 
        current_user_can( 'USER_ROLE_NAME_HERE' )
        OR current_user_can( '2ND_ROLE_NAME_HERE' )
    )
        exit( wp_redirect( $redirect ) );
}
add_action( 'admin_init', 'wpse66093_no_admin_access', 100 );