Not able to update API management isntance using powershell - azure-api-management

Question

Trying to fetch system certificates from API management instance .Then trying to remove the certificate and update the APIM instance .
APIM management instance is in INTERNAL VNET mode.
Set-AzContext -Subscription "xxxx"
$apimservice= Get-AzApiManagement -ResourceGroupName "xxxx" -Name "xxxx"
$apimservice.SystemCertificates
$apimservice.SystemCertificates.Clear()
Set-AzApiManagement -InputObject $apimservice
ERROR:
Set-AzApiManagement : 'SubnetResourceId' does not match expected pattern '^/subscriptions/[^/]*/resourceGroups/[^/]*/
providers/Microsoft.(ClassicNetwork|Network)/virtualNetworks/[^/]*/subnets/[^/]*$'.
At line:8 char:1
+ Set-AzApiManagement -InputObject $apimservice
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : CloseError: (:) [Set-AzApiManagement], ValidationException
+ FullyQualifiedErrorId : Microsoft.Azure.Commands.ApiManagement.Commands.SetAzureApiManagement

Answer 1

Looking to your script it seems correct.
So far as we have not all the configuration as yours we have tried to reproduce the minimal as we can and it works at our end.
Could you please make sure you are using connect-azaccount before using the set-azcontext .
And try to use the latest module of az PowerShell module as 8.0.
Set-AzApiManagement : 'SubnetResourceId' does not match expected
pattern '^/subscriptions/[^/]/resourceGroups/[^/]/
providers/Microsoft.(ClassicNetwork|Network)/virtualNetworks/[^/]/subnets/[^/]$'.
For the error:-
Make sure that you have correctly added your resource group as mentioned in portal.
For more information please refer the below Links:-
MICROSOFT DOCUMENTATION|Set-AzApiManagement
MS Q&A For Similar error| resourceGroupName' does not match expected pattern'^[-\w._()]+[ & Getting invalid status code conflict while running New-AzRoleAssignment in powershell.