Cannot use aks update --outbound-type userDefinedRouting

[solita-tonimiettinen]

Describe the bug

Cannot change outbound type in existing cluster with aks update.

Related command

$ az aks update -g rg-aks -n aks-name --outbound-type userDefinedRouting
--vnet-subnet-id must be specified for userDefinedRouting and it must be pre-configured with a route table with egress rules

$ az aks update -g rg-aks -n aks-name --outbound-type userDefinedRouting --vnet-subnet-id "/subscriptions/.../subnets/aks-subnet"
unrecognized arguments: --vnet-subnet-id /subscriptions/.../subnets/aks-subnet

Errors

--vnet-subnet-id must be specified for userDefinedRouting and it must be pre-configured with a route table with egress rules
with --vnet-subnet-id:
unrecognized arguments: --vnet-subnet-id /subscriptions/.../subnets/aks-subnet

Issue script & Debug output

cli.knack.cli: Command arguments: ['aks', 'update', '-g', 'rg-aks', '-n', 'aks', '--outbound-type', 'userDefinedRouting', '--vnet-subnet-id', '/subscriptions/.../subnets/aks-subnet', '--debug']
cli.knack.cli: __init__ debug log:
Enable color in terminal.
cli.knack.cli: Event: Cli.PreExecute []
cli.knack.cli: Event: CommandParser.OnGlobalArgumentsCreate [<function CLILogging.on_global_arguments at 0x7f9abfd6ad40>, <function OutputProducer.on_global_arguments at 0x7f9abfadc5e0>, <function CLIQuery.on_global_arguments at 0x7f9abfb09b20>]
cli.knack.cli: Event: CommandInvoker.OnPreCommandTableCreate []
cli.azure.cli.core: Modules found from index for 'aks': ['azext_aks_preview', 'azure.cli.command_modules.acs', 'azure.cli.command_modules.serviceconnector']
cli.azure.cli.core: Loading command modules...
cli.azure.cli.core: Loaded command modules in parallel:
cli.azure.cli.core: Name                  Load Time    Groups  Commands
cli.azure.cli.core: serviceconnector          0.333        20       331
cli.azure.cli.core: acs                       0.448        18        96
cli.azure.cli.core: Total (2)                 0.450        38       427
cli.azure.cli.core: These extensions are not installed and will be skipped: ['azext_ai_examples', 'azext_next']
cli.azure.cli.core: Loading extensions:
cli.azure.cli.core: Name                  Load Time    Groups  Commands  Directory
cli.knack.cli: Event: CommandLoader.OnLoadCommandTable []
cli.azure.cli.core: aks-preview               0.071        30       141  /home/me/.azure/cliextensions/aks-preview
cli.azure.cli.core: Total (1)                 0.071        30       141  
cli.azure.cli.core: Loaded 54 groups, 489 commands.
cli.azure.cli.core: Found a match in the command table.
cli.azure.cli.core: Raw command  : aks update
cli.azure.cli.core: Command table: aks update
cli.knack.cli: Event: CommandInvoker.OnPreCommandTableTruncate [<function AzCliLogging.init_command_file_logging at 0x7f9abebd8040>]
cli.azure.cli.core.azlogging: metadata file logging enabled - writing logs to '/home/me/.azure/commands/2026-04-16.11-37-18.aks_update.7952.log'.
az_command_data_logger: command args: aks update -g {} -n {} --outbound-type {} --vnet-subnet-id {} --debug
cli.knack.cli: Event: CommandInvoker.OnPreArgumentLoad [<function register_global_subscription_argument.<locals>.add_subscription_parameter at 0x7f9abec2dbc0>]
cli.knack.cli: Event: CommandLoader.OnLoadArguments []
cli.knack.cli: Event: CommandInvoker.OnPostArgumentLoad []
cli.knack.cli: Event: CommandInvoker.OnPostCommandTableCreate [<function register_ids_argument.<locals>.add_ids_arguments at 0x7f9abea58400>, <function register_cache_arguments.<locals>.add_cache_arguments at 0x7f9abea585e0>, <function register_upcoming_breaking_change_info.<locals>.update_breaking_change_info at 0x7f9abea58680>]
cli.knack.cli: Event: CommandInvoker.OnCommandTableLoaded []
cli.knack.cli: Event: CommandInvoker.OnPreParseArgs []
cli.azure.cli.core.command_recommender: "--vnet-subnet-id" is an invalid parameter for command "aks update".
urllib3.connectionpool: Starting new HTTPS connection (1): app.aladdin.microsoft.com:443
urllib3.connectionpool: https://app.aladdin.microsoft.com:443 "GET /api/v1.0/suggestions?query=%7B%22command%22%3A+%22aks+update%22%2C+%22parameters%22%3A+%22%22%7D&clientType=AzureCli&context=%7B%22versionNumber%22%3A+%222.84.0%22%2C+%22errorType%22%3A+%22UnrecognizedArguments%22%2C+%22correlationId%22%3A+%2244023f82-024b-4743-98ef-b285c14ae630%22%2C+%22subscriptionId%22%3A+%22ae6cbacb-2eac-42cc-978e-516b8ef7628d%22%2C+%22eventId%22%3A+%22a8d4b4af-da3c-4ead-be5b-a23036be46f5%22%7D HTTP/1.1" 200 None
cli.azure.cli.core.command_recommender: "--vnet-subnet-id" is an invalid parameter for command "aks update".
cli.azure.cli.core.azclierror: NoneType: None

cli.azure.cli.core.azclierror: unrecognized arguments: --vnet-subnet-id /subscriptions/.../subnets/aks-subnet
az_command_data_logger: unrecognized arguments: --vnet-subnet-id /subscriptions/.../subnets/aks-subnet

Expected behavior

Outbound type is updated to user defined routing

Environment Summary

{
  "azure-cli": "2.84.0",
  "azure-cli-core": "2.84.0",
  "azure-cli-telemetry": "1.1.0",
  "extensions": {
    "aks-preview": "20.0.0b2",
    "ml": "2.41.1",
    "ssh": "2.0.6"
  }
}

Additional context

Azure Cloud Shell, Free AKS tier. Have tried with and without aks-preview extension.

[azure-client-tools-bot-prd]

Hi @solita-tonimiettinen,

2.84.0 is not the latest Azure CLI(2.85.0).

If you haven't already attempted to do so, please upgrade to the latest Azure CLI version by following https://learn.microsoft.com/en-us/cli/azure/update-azure-cli.

[yonzhan]

Thank you for opening this issue, we will look into it.

[microsoft-github-policy-service]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @mbifeld, @FumingZhang, @andyliuliming, @act-observability-squad.

[microsoft-github-policy-service]

🔔 Routing this issue to @act-observability-squad.

[microsoft-github-policy-service]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @mbifeld, @FumingZhang, @andyliuliming, @act-observability-squad.