UCS 4.4-5 - Configuration error in Nagios

Hi folks, UCS maniacs!

After one of update in July 2020 nagios service doesn’t up. The problem was like this:

Running pre-flight check on configuration data...

Checking objects...
Error: Service check command 'check_univention_ad_connector' specified in service 'UNIVENTION_ADCONNECTOR' for host 'dcb.mydomain' not defined anywhere!
        Checked 37 services.
        Checked 2 hosts.
        Checked 1 host groups.
        Checked 0 service groups.
        Checked 1 contacts.
        Checked 2 contact groups.
        Checked 191 commands.
        Checked 4 time periods.
        Checked 0 host escalations.
        Checked 0 service escalations.
Checking for circular paths...
        Checked 2 hosts
        Checked 0 service dependencies
        Checked 0 host dependencies
        Checked 4 timeperiods
Checking global event handlers...
Checking obsessive compulsive processor commands...
Checking misc settings...

Total Warnings: 0
Total Errors:   1

***> One or more problems was encountered while running the pre-flight check...

When I removed host from UMC->Devices->Nagios->UNIVENTION_ADCONNECTOR proccess goes up and all is green in my nagios panel.

Why that happened? What is UNIVENTION_ADCONNECTOR for? Is it OK to deactivate it by this way?

Thanks in advance