Score:0

Azure Virtual Machine Scale Set error: The selected virtual network has a default subnet with a reserved name

us flag

What makes a subnet as default if not the name or lower starting IP? Getting below error on selecting a virtual network:

enter image description here

Below are the subnets configured
Name                IPv4            Available IPs
default             10.0.0.0/24     251
GatewaySubnet       10.0.1.0/24     availability dependent on dynamic use
AzureFirewallSubnet 10.0.3.0/26     56
Bot-subnet          10.0.4.0/24     251

Edit: Overall I'm trying to create a Service Fabric and Virtual Machine Scale set using Bicep, and then tried to create the VMSS manually mentioned above through Portal. Either way do not work. Creating Service Fabric through Portal create VMSS and many other resources automatically, but when doing it through code I first created VMSS and faced above mentioned problem.

Score:1
cn flag

I had the same problem and contacted support. Though i did not find out what the "default" subnet would be and how it was chosen, we found a workaround while they escalate the issue.

You can create the VMSS using az cli (and i assume also using the powershell module) like this:

az vmss create \
-n <vmss-name> \
-g <resource-group-name> \
--image Win2019Datacenter \
--location <location> \
--instance-count 0 \
--disable-overprovision \
--upgrade-policy-mode manual \
--lb "" \
--computer-name-prefix "prefix-" \
--vm-sku "Standard_D4s_v4" \
--public-ip-address "" \
--subnet /subscriptions/<subscriptionid>/resourceGroups/<resource-group-name>/providers/Microsoft.Network/virtualNetworks/<vnet-name>/subnets/<subnet-name> \
--admin-username username \
--admin-password "whatever"

Check az vmss create --help for the full list of parameters. My guess is it is a glitch in the portal, which will be fixed soon.

mangohost

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