---
name: vpc-2026-09-01-instance-profile-vcpu-count-migration
title: Updating to the 2026-09-01 version (instance profile vCPU count change)
description: As described in the VPC API reference versioning policy, most changes to the VPC APIs are fully backward compatible and are made available to all clients, regardless of the API version the client requests. However, the `2026-09-01` release of the VPC API necessitated incompatible changes in support of updated modeling of instance profile vCPU count values.
last-updated: 2026-09-01
---

> ## Documentation Index
> The table of contents for this documentation set is at https://cloud.ibm.com/docs/vpc?format=markdown
> The index for all IBM Cloud docs is at: https://cloud.ibm.com/docs/llms.txt
> Use these files to discover more information as needed.

# Updating to the 2026-09-01 version (instance profile vCPU count change)
{: #2026-09-01-instance-profile-vcpu-count-change}

As described in the VPC API reference [versioning](https://cloud.ibm.com/docs/apis/vpc/latest#api-versioning) policy, most changes to the VPC APIs are fully backward compatible and are made available to all clients, regardless of the API version the client requests. However, the `2026-09-01` release of the VPC API necessitated incompatible changes in support of updated modeling of instance profile vCPU count values.

Before you adopt the release version `2026-09-01` or later, review the changes described in this migration guidance that might require you to update your client.

## Changed instance profile properties
{: #changed-properties-instance-profile-api-version-2026-09-01}

The following properties have changed for API requests that use a `version` query parameter of `2026-09-01` or later.

When [retrieving](https://cloud.ibm.com/docs/apis/vpc/latest#get-instance-profile) or [listing](https://cloud.ibm.com/docs/apis/vpc/latest#list-instance-profiles) instance profiles, the following properties have changed for API requests that use a `version` query parameter of `2026-09-01` or later.

| Changed property        | Behavior change |
|-------------------------|-------------------------------------------------|
| `vcpu_count`            | fixed value response will be replaced by array. |
| `supported_vcpu_count`  | Removed from the response. |
{: caption="Changed properties when retrieving or listing instance profiles." caption-side="bottom"}

For API `version` query parameter of `2026-08-31` or earlier, `vcpu_count` is returned as a fixed-value, and `supported_vcpu_count` contains the supported enum values. For API version `2026-09-01` or later, `supported_vcpu_count` is removed from the response and the `vcpu_count` property now returns those supported values directly as an array of enum values.

## Action needed
{: #action-needed-instance-profile-api-version-2026-09-01}

Before you specify the `version` query parameter of `2026-09-01` or later, follow these actions to avoid regressions in client functionality.

if your client reads `supported_vcpu_count.values`, update your client code to read `vcpu_count.values` instead.

If your client implementation is based on `vcpu_count` containing a fixed `value`, update the code to support the documented response forms for `vcpu_count`, including enum-based, range-based, and dependent values.

If your clients continue to specify version `2026-08-31` or earlier, no changes are required.
{: note}

### Client migration
{: #client-migration-instance-profile-api-version-2026-09-01}

Before you migrate a client to API version `2026-09-01` or later, review your code that uses the following methods:

- `GET /instance/profiles/{name}`
- `GET /instance/profiles`

Review the changes that were announced in the [API change log](https://cloud.ibm.com/docs/vpc?topic=vpc-api-change-log&format=markdown#1-september-2026), and verify that your code adopts these changes in a manner that is appropriate for your programming language.

## Example
{: #example-instance-profile-api-version-2026-09-01}

These examples compare differences between before and after the `2026-09-01` versioned change.

### Retrieving an instance profile
{: #retrieve-instance-profile-api-version-2026-09-01}

The example response is from a request made using API version `2026-08-31` or earlier. The response includes `vcpu_count` as a fixed value and `supported_vcpu_count` as the list of supported values.

```json
{
  "name": "bx2-custom",
  "resource_type": "instance_profile",
  "vcpu_count": {
    "type": "fixed",
    "value": 4
  },
  "supported_vcpu_count": {
    "default": 4,
    "type": "enum",
    "values": [4]
  }
}
```
{: codeblock}

The example below shows a response for requests made using API version 2026-09-01 or later.In this version, vcpu_count is returned as an enum value, and supported_vcpu_count has been removed from the response.

```json
{
  "name": "bx2-custom",
  "resource_type": "instance_profile",
  "vcpu_count": {
    "default": 4,
    "type": "enum",
    "values": [4]
  }
}
```
{: codeblock}