A common error with Set-AzureVNetGatewayKey

Recently I’ve helped a customer configuring a hub-and-spoke topology where they had one VNET at the ‘Centre’ configured with VPN to their on-premises network which then needed to be connected to multiple ‘satellite’ VNETs using VNET-VNET connectivity.

A very good walkthrough of how to configure advanced topologies and multi-hop networks on Azure can be found here

We’ve taken a step-by-step approach so we first established cross-premises connectivity using the portal UI, we then started to add the satellite networks one by one.

On the satellite sites we never had any issues as we could do everything through the UI. Expanding the connectivity on the central network required editing the configuration XML to link to multiple networks and after the first two, arguably as we were growing overly confident, we got the following error when trying to set the pre-shared key for the VPN gateway on the central network –

Set-AzureVNetGatewayKey -VNetName CentralVnet -LocalNetworkSiteName SatelliteVnet3 -SharedKey A1B2C3

Set-AzureVNetGatewayKey : BadRequest: The specified local network site name SatelliteVnet3′ is not valid or could not be found.

It took us a little while to figure out what we were missing as we didn’t get this every time. Turns out that occasionally we got ahead of ourselves and tried to update the shared key before importing the updated network configuration xml with the added link between the central network and the satellite one. Given that they key is set on the combination of the two, if you try to set it before making the actual link the command, understandably, fails (although the error message could be a bit clearer)

As an aside – we’ve also seen the following error when executing this command –

Set-AzureVNetGatewayKey : An error occurred while sending the request.

This happened when we delayed long enough for the AAD token in the PowerShell session and we could verify that by trying to execute any other command such as Get-AzureVNetGatewayKey or even Get-Azure Subscription. Using Add-AzureAccount to obtain a new token solved that one easily enough.

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