Troubleshoot host preparation issues in NSX
To troubleshoot host preparation issues in NSX, you must first navigate to Networking & Security then click Installation -> Host Preparation. Confirm that all your hosts have a green check mark next to them.
As you can see, everything in my lab is good, but if you see any red x marks you will you need to try to figure out what happened. The first thing you can try, is to force sync by clicking the link next to the error and select Force-Sync to try to repair the problem.
If the force sync does not work, you will need to dig a little deeper. Sometimes you will need to navigate to Home -> Administration -> vCenter Server Extensions then double click on the vSphere ESX Agent Manager link.
From there, select Monitor -> Events and look for any error messages relating to NSX and troubleshoot from there. You can also look at the NSX Manager logs by logging into the NSX Manager appliance via SSH, and type show manager log
Search for the error message you are seeing in this log for more information. I was able to reproduce any issues currently, but I have looked into this log to successfully troubleshoot host preparation issues.
nsxmgr-l-01a> show manager log