,
Please perform the following tasks:
1. Un-register update manager extension from vC MOB --> https://kb.vmware.com/s/article/1025360
Update manager extension: com.vmware.vcIntegrity
2. Register update manager: /usr/lib/vmware-updatemgr/bin/updatemgr-utility.py register-vc
3. Stop and start update manager service:
service-control --stop vmware-updatemgr
service-control --start vmware-updatemgr
Hope that helps