Problem with Check-mk monitoring Discovery

Hello all
I have Check-mk monitoring Linux Ubuntu 18.4
and i have problem with one Error …
CRIT - no unmonitored services found, no vanished services found, no new host labels, [snmp] Cannot fetch system description OID . This might be OK for some bogus devices. In that case please configure the ruleset “Hosts without system description OID” to tell Check_MK not to fetch the system description and system object OIDs. CRIT

Can anyone help me? :face_with_head_bandage: