I have a VPN gateway which is failed state since it doesn't have any virtual hub attached with it.

ubuntu@ip-172-31-19-1:~$ az network vpn-gateway show \
  -g QA_Aug \
  -n mcn-vpngw-sc-qcrn9z-japaneast \
  --query "{name:name,location:location,state:provisioningState,hub:virtualHub.id}" \
  -o json
{
  "hub": null,
  "location": "japaneast",
  "name": "mcn-vpngw-sc-qcrn9z-japaneast",
  "state": "Failed"
}

So, i have created a hub in the same region to attach the orphaned VPN to it, but when i try to attach it with the Hub I am getting InternalServerError.

ubuntu@ip-172-31-19-1:~$ az network vhub show   -g QA_Aug   -n new-hub   --query "{name:name,location:location,state:provisioningState,id:id}"   -o json      {
  "id": "/subscriptions/e3de723e-e527-4610-85a4-87a3b1d7a37c/resourceGroups/QA_Aug/providers/Microsoft.Network/virtualHubs/new-hub",
  "location": "japaneast",
  "name": "new-hub",
  "state": "Succeeded"
}


ubuntu@ip-172-31-19-1:~$ az network vpn-gateway update \
  -g QA_Aug \
  -n mcn-vpngw-sc-qcrn9z-japaneast \
  --vhub "/subscriptions/e3de723e-e527-4610-85a4-87a3b1d7a37c/resourceGroups/QA_Aug/providers/Microsoft.Network/virtualHubs/new-hub"
(InternalServerError) An error occurred.
Code: InternalServerError
Message: An error occurred.

Now I am neither able to delete the VPN gateway nor make it provisioned success. How this VPN can be deleted from the subscription?