Are you running Role Scoper version 1.2.7, and seeing this when all plugins except Role Scoper are deactivated? Also after switching temporarily to the default theme?
Does it occur right after you activate Role Scoper, with other wp-admin URL(s), or both?
Is this a Multisite installation? If so, are you logged as a limited administrator (not a super admin of all sites)?
Something strange is happening on your installation because normally the code that generated that error would not even execute for a logged Administrator (which you presumably are to activate the plugin).
To help me diagnose this, can you temporarily modify permission_lib_rs.php as follows:
change:
if ( $reqd_caps = array_merge( array_keys($admin_caps), array_keys($delete_caps) ) ) {
if ( ! defined('DISABLE_QUERYFILTERS_RS') && $scoper->cap_interceptor->user_can_for_any_object( $reqd_caps ) )
$return = true;
}
to:
if ( $reqd_caps = array_merge( array_keys($admin_caps), array_keys($delete_caps) ) ) {
if( ! method_exists( $scoper->cap_interceptor, 'user_can_for_any_object' ) )
agp_bt_die();
if ( ! defined('DISABLE_QUERYFILTERS_RS') && $scoper->cap_interceptor->user_can_for_any_object( $reqd_caps ) )
$return = true;
}
You will also need to temporarily add this to wp-config.php, above the "stop editing" line:
define( 'RS_DEBUG', true );