[Microsoft.ManagedIdentity/userAssignedIdentities]: Properties incorrectly flagged as read-only for User Assigned Managed Identities

[EdwinGarcia]

Resource Type

Microsoft.ManagedIdentity/userAssignedIdentities

Api Version

2025-01-31-preview

Issue Type

Property(s) inaccurately marked read-only/write-only

Other Notes

When I try to change the properties of my User Assigned Managed Identities (UAMI), I get the following warning:

The property "properties" is read-only. Expressions cannot be assigned to read-only properties. If this is a resource type definition inaccuracy, report it using https://aka.ms/bicep-type-issues.bicep[BCP073](https://aka.ms/bicep/core-diagnostics#BCP073)

I know System Assigned Managed Identities (SAMI) are read-only but you can modify UAMI properties. Happens across multiple API versions, not just the one I specified.

Bicep Repro

resource UAMIName 'Microsoft.ManagedIdentity/userAssignedIdentities@2025-01-31-preview' = {
  location: 'westus3'
  tags: {}
  name: 'UAMIName'
  properties: {
    isolationScope: 'Regional'
  }
}

Confirm

• I have read the troubleshooting guide and looked for duplicates.