diff --git a/src/azure-cli/azure/cli/command_modules/acs/azurecontainerstorage/_validators.py b/src/azure-cli/azure/cli/command_modules/acs/azurecontainerstorage/_validators.py
index 7b2d434b9e5..ed3774581d4 100644
--- a/src/azure-cli/azure/cli/command_modules/acs/azurecontainerstorage/_validators.py
+++ b/src/azure-cli/azure/cli/command_modules/acs/azurecontainerstorage/_validators.py
@@ -661,7 +661,7 @@ def _validate_nodepools(  # pylint: disable=too-many-branches,too-many-locals
                         'and retry the Azure Container Storage operation.'
                     )
             vm_size = agentpool.get("vm_size")
-            if vm_size is not None:
+            if vm_size is not None and vm_size != "":
                 cpu_value, nvme_enabled = get_vm_sku_details(vm_size.lower())
                 if cpu_value is None or nvme_enabled is None:
                     raise UnknownError(
diff --git a/src/azure-cli/azure/cli/command_modules/acs/managed_cluster_decorator.py b/src/azure-cli/azure/cli/command_modules/acs/managed_cluster_decorator.py
index 3cf9e588d35..c3d4ddd01e7 100644
--- a/src/azure-cli/azure/cli/command_modules/acs/managed_cluster_decorator.py
+++ b/src/azure-cli/azure/cli/command_modules/acs/managed_cluster_decorator.py
@@ -8825,7 +8825,7 @@ def update_azure_container_storage(self, mc: ManagedCluster) -> ManagedCluster:
             except Exception as ex:
                 raise UnknownError(
                     f"An error occurred while checking the version of Azure Container Storage"
-                    f"extension installed on the cluster: {str(ex)}"
+                    f" extension installed on the cluster: {str(ex)}"
                 ) from ex
 
             disable_azure_container_storage_v1 = disable_azure_container_storage_param is not None and is_container_storage_v1_extension_installed