BatchPatch Windows update: Error 1601

There are two primary flavors of error 1601:

Windows Update: Error 1601: Failed to retrieve WMI info. Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))

“Access is denied” means that you have a permissions problem. Please follow the steps outlined on the following page to rectify the issue: BatchPatch Authentication In Domains And Non Domain Workgroups

Windows Update: Error 1601: Failed to retrieve WMI info. The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)

“RPC server is unavailable” is typically caused by one of the following things:

1. The large majority of occurrences of “RPC server is unavailable” are due to a firewall blocking communication. If BatchPatch makes a query to a remote server but does not receive a response, this is the error that you will see. Windows firewall, a third-party software firewall, or a network firewall is likely preventing communication to the target host. Make sure your firewall is set to allow the appropriate communications to pass through. In the case of this particular error, WMI communications must be allowed. While you could, of course, disable the firewall altogether, this is generally not recommended in most cases unless it’s just to do a quick test to determine that the firewall is, in fact, the cause of the issue. Depending on your environment, it might be ok to briefly turn off the firewall as a test, but be mindful that there are many situations where a firewall should not ever be turned off even for a moment. For instructions on configuring Windows firewall to work with BatchPatch, see this page: Using BatchPatch With Windows Firewall
2. The second most common reason why you might experience this “RPC server is unavailable” error is due to the remote computer being offline. This RPC error is what you’ll see if there is simply no response to the initial query that BatchPatch makes when you attempt a Windows Update action. Make sure the target computer is online. If the computer is online, try the IP address instead of the host name to ensure that isn’t some kind of name resolution issue. If the computer is definitely online but you’re still getting this RPC error even when using the IP address instead of the host name, refer back to the item above and check the firewall since this error is almost always due to a firewall blocking communications.
3. Check to make sure that RPC (Remote Procedure Call) service is running on the target computer. The service should be started and set to ‘Automatic’. If the RPC service is not running on the target computer, not only will BatchPatch not be able to connect to it, but it’s likely that you’re going to be experiencing a lot more issues with that target computer in addition to BatchPatch not working. It’s highly unlikely that you’ll ever find this service NOT running since Windows needs it to be running for so many reasons, but do a quick check just to make sure.
4. In some cases this error might be caused by anti-virus or host intrusion prevention/protection software or some other similar security software suite blocking the connection.

If you’ve gone through each of the items above and you’re still having issues, please see Troubleshooting Common Errors in BatchPatch

If you’re seeing a different 1601 error message, such as Windows Update: Error 1601: Failed to retrieve WMI info. Invalid class, or Windows Update: Error 1601: Failed to retrieve WMI info. Invalid namespace, then you might have an issue with WMI on the target computer. The first best bet is usually just to reboot the target computer to ensure that the issue wasn’t transient. Assuming the reboot does the not resolve the problem, please review the various steps at this page for resolutions to many/most WMI failures: WMI: Missing or Failing WMI Providers or Invalid WMI Class