Cannot fetch system description OID .1.3.6.1.2.1.1.1.0 SNMP

CMK version: 2.4.0p12
Hello,

I have seen this error message on multiple devices after upgrading the checkmk. No firewall rules changes or SNMP credentials changed. What could be the reason?

Error message:

Services: all up to date, Host labels: all up to date, [snmp] Cannot fetch system description OID .1.3.6.1.2.1.1.1.0. Please check your SNMP configuration. Possible reason might be: Wrong credentials, wrong SNMP version, Firewall rules, etc.CRIT, execution time 15.0 sec

In another devices with same model :

[API/agent] host configuration requires a datasource but none configuredCRIT, [snmp] Cannot fetch system description OID .1.3.6.1.2.1.1.1.0. Please check your SNMP configuration. Possible reason might be: Wrong credentials, wrong SNMP version, Firewall rules, etc.CRIT, [piggyback] Success (but no data found for this host), Missing monitoring data for all pluginsWARN, execution time 15.0 sec