I am the admin for a software test lab. I have a single vCenter appliance that I recently upgraded from 5.5. I have one test host running 5.1 for test purposes, and after the upgrade, it keeps reporting "Unable to apply DRS resource settings on host". The problem is that this machine is not in a cluster, nor has it ever been. So I can't turn off DRS in the cluster to correct this. I can't find any DRS settings that it is trying to use. I don't know what to do to clear this error, and I have a couple testers saying that they are getting complaints from the developers saying that the bugs they report are because the host is not configured properly. (Bunch of bunk, if you ask me. They're looking for any reason to not look into the bugs.) Anyone have any ideas?
I've actually never seen this error message myself, but what might be worth a try is to create a temporary new cluster for this host, then reconfigure (disable DRS if enabled) and remove the host from the cluster again. Maybe this resolves the issue!?
Can you try to restart the management services on the ESXi host? Try services.sh restart. That took care of it in my environment.
You might also have a look at VMware KB: ESX/ESXi host in vCenter Server reports the error: Unable to apply DRS resource settings ... and VMware KB: Applying DRS settings to an ESX or ESXi host generates an error as well.
Please follow the steps below to fix the issue :
Add the host to a cluster with DRS, Then disable the DRS on this cluster, Remove the host from the cluster, Enable the DRS back to the cluster.
I've seen this issue before :
What could have happened is that this host was for some point of time in a cluster and it has gone not responding or disconnected and you have made some changes on the DRS then the host connected back but it's not aware of the changes you have made on the DRS settings and it can cause this issue.