Ran into a problem a few months ago while building a MSCS (Microsoft Clustering Services) while verifying the cluster nodes when I would continue to get the following message:
An error occurred while executing the test. There was an error verifying the firewall configuration. An item with the same key has already been added.
After searching for awhile for the answer, I found that this was because the NICs on the virtual machines had the same GUIDs and MSCS doesn’t like that. This generally wouldn’t be a problem if the servers were physical because the GUIDs would be different but this customer opted to deploy the cluster in their vSphere environment and since the servers were deployed from templates, the GUIDs ended up being the same. One of the blog posts I found indicated that I can remove the NIC from within Windows but when I tried doing so through device manager, the GUID ended up being the same. What I ended up doing to resolve the problem was:
- Uninstall the NIC from Device Manager within Windows.
- Shut off the virtual machine.
- Removed the NIC by editing the virtual machine’s settings from vCenter, click OK.
- Edit the virtual machine’s settings and add a new NIC, click OK.
Once Windows completed the startup, I went into the registry and can now see the new NIC haven’t a different GUID.