My auth has suddenly quit working today (9/18)

[ehagenmsft]

I have created several copilot skills that require authentication. All were working up until yesterday, but now today they are all failing with authentication issues. I keep getting this error:

The Kusto MCP is unavailable, and the REST fallback failed Azure authentication with  AADSTS901001  due to an invalid  software_agent_id . Azure CLI requires a fresh  az logout  /  az login  authentication before the query can run.

az login is not authenticating for me. It keeps saying "broswer-based sign-in is still injecting the invalid agent ID, so I'm switching to device-code flow. Device-code flow fails to authenticate me.

This issue is severely restricting my work, so assistance would be greatly appreciated. Thanks!

[yonzhan]

Thank you for opening this issue, we will look into it.

[microsoft-github-policy-service]

🔔 Routing this issue to @Azure/act-identity-squad.

[x-engineering-agent]

To distinguish an Azure CLI sign-in failure from the Copilot/Kusto integration, please share:

• Your Azure CLI version (az version), operating system, shell, and how Azure CLI was installed.
• The exact login commands and flags you used, and whether they were run directly in a terminal or by a Copilot skill.
• Whether the problem also occurs in a terminal outside Copilot. For browser and device-code sign-in, provide the actual sanitized terminal error, rather than the assistant's explanation, and say whether either flow succeeds.

Please omit tokens, device codes, credentials, and complete debug logs. The error code and sanitized error text are sufficient. I'll pick this up automatically once you reply.

[microsoft-github-policy-service]

🔔 Routing this issue to @Azure/act-identity-squad.

[ehagenmsft]

Looks like this self-resolved after 48 hours.