Unauthorized error while pushing docker image to ACR

Question

Unauthorized error while pushing docker image to ACR

Hungry Panda 45

Hi,

I've created a docker image in my Azure Virtual machine and trying to push the image to ACR. I was able to login successfully but the docker push is giving me authorization error.

I have tried with all the combo of the below fields while creating the ACR, :

Domain name label scope: Tenant Reuse/ Unsecure
Pricing Plan: Basic/ Standard
Role assignment permissions mode: RBAC + ABAC / RBAC

Once done, I've checked the "Admin user" under the Access keys and was able to login successfully using username and password. I've checked the Role Assignments from IAM and it's "Owner".

But getting this error while doing docker push:

unauthorized: {"errors":[{"code":"UNAUTHORIZED","message":"authentication required, visit https://aka.ms/acr/authorization for more information. CorrelationId: 14aa440f-e0f4-4473-b69e-62159e0d622a"}]}

I tried to check the logs (under Monitorin) using the CorrelationId, but keep getting error while trying to execute any query (following the demo video).What am I doing wrong?

Thanks and Regards

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Answer 1

Muskan Tomar 470 Microsoft Employee

Hey!

If you're seeing an unauthorized error during docker push to ACR, even after a successful docker login, check the following:

Correct image tag – Make sure your image is tagged with the ACR login server name: docker tag myimage <yourregistry>.azurecr.io/myimage
Admin user enabled – Confirm that the Admin user toggle is ON under ACR → Access keys.

Proper role assignment – Ensure your identity (user/VM) has AcrPush or Owner role on the ACR resource, not just at subscription/resource group level.

Auth token issues – Try docker logout <yourregistry>.azurecr.io and login again to clear stale tokens.

Also, worth checking/reconfirming ---- If using Managed Identity (e.g., from a VM), use az acr login --name <yourregistry> instead of docker login.

Let me know if this helps!

Hungry Panda 45 Reputation points

2025-07-21T16:50:02.0366667+00:00

Hi Muskan Tomar,

Thank you for the response. In point 2, did you mean this?

If yes, I had already mentioned doing that but still didn't work.

To check the Role assignment, did you mean from here?

I'm not sure about the Managed Identity part, can you explain a bit more?
I'm accessing ACR from my VM in Azure.

Ankit Yadav 5 Microsoft External Staff Moderator

Hello @Hungry Panda ,Can you please confirm if you are using either:

az acr login as your actual session (preferred),
or
docker login with admin credentials if admin user enabled.

I'm not sure about the Managed Identity part, can you explain a bit more?

Sure, Managed Identity is an authentication method in Azure that allows applications to securely access Azure resources without needing to manage credentials like passwords or connection strings. To know more on how to use it in ACR, please refer: Managed Identity Authentication for ACR - Azure Container Registry | Azure Docs and Deploy container image from Azure Container Registry using a managed identity - Azure Container Instances | Microsoft Learn

Additionally, please see below table for comparison of authentication methods for Azure Container Registry.

Method	Works for Push	Secure	Best For	Setup Steps
Admin user (username/password)	Yes	Medium	Quick tests	Enable admin user, docker login -u ... -p ...
Azure AD user/service principal	Yes	High	Automation	`az acr login` + assign AcrPush/Owner/Contributor
Managed Identity (VM/Service)	Yes	Highest	Prod/VM	Assign MI to VM + AcrPush role on ACR, use `az acr login` on VM

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Unauthorized error while pushing docker image to ACR

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