API version 2026-03-01-preview for Microsoft.insights/actionGroups does not work

Question

API version 2026-03-01-preview for Microsoft.insights/actionGroups does not work

Marcus Holmberg 0

I am seeing Azure Policy evaluation failures with Compliance reason 'UnsupportedApiVersion' on all resources for a policy that is evaluation alert Action Groups. This is likely due to "The latest API version is always used during compliance evaluation on existing resources." - see below.

Reviewing an Action Group resource in the portal by clicking JSON View, the latest API version is listed as 2026-03-01-preview. Choosing this version gets stuck in an endless loop but gives this error in the background (HTTP 400):

{ "Error": { "Code": "UnsupportedApiVersion", "Message": "The HTTP resource that matches the request URI '<readacted>/providers/microsoft.insights/actionGroups/my-action-group' does not support the API version '2026-03-01-preview'." } }

Any other available API version, like 2025-09-01-preview or 2024-10-01-preview, swiftly returns an answer.

The Change Log for this API does not show any information for versions higher than 2024-10-01-preview.

Edit: We have tried to re-register the Microsoft.Insights provider.

Suchitra Suregaunkar 13,995 Reputation points Microsoft External Staff Moderator

2026-05-06T16:14:28.1466667+00:00

Hello Marcus Holmberg

Thank you for posting your query on Microsoft Q&A platform.

We are looking into this issue and will keep you posted updates.

Thanks,

Suchitra.
Suchitra Suregaunkar 13,995 Reputation points Microsoft External Staff Moderator

2026-05-06T17:01:22.09+00:00

Hello Marcus Holmberg

The Azure portal's JSON View is listing 2026-03-01-preview as the latest API version for Microsoft.Insights/actionGroups. However, this API version is not actually supported by the resource provider backend, which is why you're getting the HTTP 400 error with UnsupportedApiVersion.

This can be confirmed from the official ARM template reference for Microsoft.Insights/actionGroups, which lists the following supported API versions — the highest being 2024-10-01-preview:

2017-04-01, 2018-03-01, 2018-09-01, 2019-03-01, 2019-06-01, 2021-09-01, 2022-04-01, 2022-06-01, 2023-01-01, 2023-09-01-preview, 2024-10-01-preview

Reference: Microsoft.Insights resource types – All API versions

Additionally, the API change log for microsoft.insights/actionGroups does not contain any entry beyond 2024-10-01-preview, further confirming that 2026-03-01-preview has not been released.

Reference: API change log for microsoft.insights/actionGroups

Why Azure Policy is failing:

Azure Policy uses the latest advertised API version during compliance evaluation of existing resources. Since the resource provider metadata is incorrectly exposing 2026-03-01-preview as available, the Policy engine attempts to use it for evaluation. The backend then rejects it with the UnsupportedApiVersion error, causing all Action Group resources to show as non-compliant.

For more details on how Azure Policy evaluates compliance and determines non-compliance reasons, refer to:

Determine causes of non-compliance – Azure Policy

Get compliance data – Azure Policy

Why re-registering the provider doesn't help:

Re-registering Microsoft.Insights affects the subscription's registration state with the resource provider, but it does not change which API versions the resource provider backend actually supports. This is documented under resource provider registration:

Reference: Resolve errors for resource provider registration

Recommended next step:

Since this is a mismatch between the resource provider's advertised API version metadata and what the backend actually supports, this requires a fix from the Microsoft Azure Monitor product team. I will check internally and will keep you posted updates.

There is currently no client-side workaround for this, as Azure Policy's compliance evaluation automatically picks the latest advertised API version, this behavior cannot be overridden by the end user.

Hope this helps clarify the situation. Please let us know if you have further questions.

Thanks,

Suchitra
Suchitra Suregaunkar 13,995 Reputation points Microsoft External Staff Moderator

2026-05-12T12:15:16.45+00:00

Hello Marcus Holmberg

I hope the details shared above helped in addressing your concern.

If the suggested resolution resolved the issue, kindly consider marking the answer as "Accepted" and "Upvote" it. This helps other community members who may encounter a similar issue in the future.

If you’re still experiencing the problem or need further clarification, please feel free to share additional information so we can continue investigating and assist you further.

Thanks,

Suchitra.

1 answer

Your answer

Suchitra Suregaunkar 13,995 Reputation points Microsoft External Staff Moderator

2026-05-06T16:14:28.1466667+00:00

Hello Marcus Holmberg

Thank you for posting your query on Microsoft Q&A platform.

We are looking into this issue and will keep you posted updates.

Thanks,

Suchitra.
Suchitra Suregaunkar 13,995 Reputation points Microsoft External Staff Moderator

2026-05-12T12:15:16.45+00:00

Hello Marcus Holmberg

I hope the details shared above helped in addressing your concern.

If the suggested resolution resolved the issue, kindly consider marking the answer as "Accepted" and "Upvote" it. This helps other community members who may encounter a similar issue in the future.

If you’re still experiencing the problem or need further clarification, please feel free to share additional information so we can continue investigating and assist you further.

Thanks,

Suchitra.

Answer 1

Hi ,

Thanks for reaching out to Microsoft Q&A.

This is not a bug in your policy. It is a preview API version incorrectly marked as latest but not actually usable, causing Azure Policy to fail compliance checks.

Azure Policy always evaluates resources using the latest API version advertised by the resource provider. In your case, Microsoft.Insights is exposing 2026-03-01-preview as the latest version for Action Groups. However, that version is not actually deployed or supported in your region/tenant, so any evaluation using it fails with UnsupportedApiVersion.

Why you see the mismatch:

Portal JSON view is picking up the latest advertised version
Backend API for your subscription/region does not support it yet
Policy engine blindly uses the latest version → evaluation fails
Change log not listing it confirms it is likely an incomplete or internal rollout

Important point: Re-registering the provider will not fix this because the issue is on Microsoft’s side (metadata vs actual API availability mismatch).

Please 'Upvote'(Thumbs-up) and 'Accept' as answer if the reply was helpful. This will be benefitting other community members who face the same issue.

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API version 2026-03-01-preview for Microsoft.insights/actionGroups does not work

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