Error monitoring host

Error monitoring host
Hello, I always have a problem adding the host. It used to work without problems, but after a few days it stopped When I try to add it again, this message appears

Although everything works, when adding a host, this message appears and an error appears Who can help with this so about deleting it and creating a new one bugle showing the same problem I hope for a quick solution

Look for more detailed information about monitoring errors on /var/log/one/monitor.log