• Under Networking and Security, Installation Status appears as Not Ready on the Clusters and Hosts. Clicking on Resolve does not fix the issue
• vSphere ESX Agent Manager showing Error VIB module for agent is not installed on host
• ESXi host fails to access VIBs from the vCenter Server.
• While changing from vShield Endpoint to NSX Manager, you may see Failed status for one or more hosts in a cluster.

1. Verify that DNS is configured correctly on the vCenter Server, the ESXi hosts and NSX Manager. Ensure that forward and reverse DNS resolution from vCenter Server, ESXi hosts, NSX Manager and Update Manager are working.
    
2. VMware recommends to have Network Time Protocol (NTP) configured on the environment. Verify that NTP is configured correctly.
    
3. Verify that all ports required for NSX for vSphere 6.x are not blocked by a firewall. For related information, see Network Port Requirements for VMware NSX for vSphere (2079386)
    
4. Verify that the vCenter Server Managed IP Address is configured correctly.
    
5. Verify that the VMware Update Manager is working correctly. Ensure that the Update Manager service is running.
   
   For related information, see:
   • Installing VXLAN Agent fails with ESX Agent Manager displaying the error: Agent VIB module not installed (2053782)
   • Troubleshooting VXLAN Installation in NSX for vSphere 6.x (2124894)
      
6. If non-default ports are specified during a vCenter Server deployment, ensure that these ports are not being blocked by the ESXi host firewall.
    
7. Verify that vCenter server vpxd process is listening on TCP port 8089. NSX Manager only support the default port 8089.
   
   Note: When vCenter is installed, vpxd selects a TCP port (8089, by default) for the ESX Agent Manager. If that port is in use at the time of installation, it will select the next free port (8090 or higher port).

If the issue persists even after trying the preceding steps, collect the VMware Support Script Data and file a support request with VMware Support and note this Knowledge Base article ID (2075600) in the problem description.

• In the VC system events table, you see the error:
  
  Event Message:'Installation of deployment unit failed, please check if ovf/vib urls are accessible, in correct format and all the properties in ovf environment have been configured in service attributes. Please check logs for details.', Module:'Security Fabric'
   
• In the /var/log/esxupdate.log file of the affected ESXi host, you see entries similar to:
  
  YYYY-MM-DD TIME 30Z esxupdate: BootBankInstaller.pyc: INFO: Unrecognized value "title=Loading VMware ESXi" in boot.cfg
  YYYY-MM-DD TIME 30Z esxupdate: vmware.runcommand: INFO: runcommand called with: args = '['/sbin/bootOption', '-rp']', outfile = 'None', returnoutput = 'True', timeout = '0.0'.
  
  Note: The preceding log excerpts are only examples. Date, time, and environmental variables may vary depending on your environment.