A different cause of a general WMI failure

I had an interesting case today:

A user reported that a collector had completely stopped collecting data for all its hosts. He\'d verified that the collector\'s service account was good and had the necessary permissions. I checked one of his collection tasks, and it reported

 WMITask failed. (msg=winproxy return status=400 errmsg=IWbemLocator::ConnectServer:Error: 800706ba:The RPC server is unavailable.

I ran a WMI query against the host manually and got the same result. (that the RPC server was unavailable)

As mentioned in our helpful article on WMI Troubleshooting, generally when the error is RPC server unavailable, the issue is one of basic connectivity, usually caused by a network or firewall issue blocking the WMI traffic from reaching its destination. In this case however, the user had the service account set up correctly, but the hosts had wmi.user and wmi.pass properties overriding those settings. This worked until the password for the user specified in those parameters expired, at which point all the hosts so affected ceased responding to WMI queries from the collector. Once the host parameters were removed, collection resumed immediately.