Azure VM Reporting “The network location cannot be reached”

For the past few days my TFS Admin server in Azure had been reporting that it couldn't access a share on the domain controller in the same Azure network and was reporting an The network location cannot be reached error. The server was logging on to the domain okay, could ping the DC and could resolve domain users when setting permissions on a share (for example), and other machines could see the Drop folder on the TFS Admin machine. It wasn't the DC at fault as all other machines could see it and access the share on the DC.

I spent ages Googling and checking DNS and other such settings but everything checked out normal. So I took the plunge and removed the server from the domain, removed its entry from the Computers section of Active Directory, rebooted the offending server and tried to rejoin the domain. Nooooooo! Exactly the same error message trying to join the domain with an The machine ALMTFSADMIN attempted to join the domain but failed. The error code was 1231. error in the System Event Log.

Fearing a complete rebuild of my TFS demo infrastructure coming on I desperately tried the good old netsh int ip reset command (yes it seems it can be done on a VM without trashing the network connection and possibly locking yourself out) but no change and then and I then tried uninstalling the  File and Printer Sharing for Microsoft Networks service of the network adapter. Still nothing doing!

I then came across a post where a respondent advised removing orphaned network adapters. I knew there was something funny going on here since my network adapter name was Microsoft Hyper-V Network Adapter #149 and was presumably installing a new adapter every time the machine booted from cold (ie from the Stopped (Deallocated) state). With nothing to loose I opened up Device Manager, selected View > Show hidden devices and then expanded Network adapters. Sure enough there was a monster list of orphaned Microsoft Hyper-V Network Adapter entries -- 148 to be precise. Breaking all rules about automating tasks that you do more than once I feverishly manually uninstalled all the entries bar the current one. Then rebooted. And with bated breath tried to rejoin the domain...with success!

Whew! Lucky escape this time. Follow-up actions are to find out why this is happening and how to uninstall these in a more automated way -- with the PowerShell Remove-VMNetworkAdapter cmdlet for example? Do leave a comment if you have any insight!

Cheers -- Graham