Turn off user-switching in developer support.
A request from a user who is not logged in will try to set a client property (see trace below). This will fail since [ad_conn session_id] is null - it hasn't been set yet when ds_collect_connection_info runs.
invoked from within
ad_set_client_property developer-support user_id 0
invoked from within
ds_replace_get_user_procs 1
invoked from within
ds_collect_connection_info
invoked from within
rp_filter preauth