Azure Text Translator endpoint has suddenly stopped working for unknown reason

Hey Nikita Khandare ,

A 401 Unauthorized error from the Azure Translator Text service usually indicates an authentication or endpoint mismatch, even if the same key and endpoint were working earlier. Since the issue is also reproducible from the Try It tool, this suggests the problem may be with the Translator resource configuration rather than your client code.

You may try the following checks:

Verify endpoint type: Global Translator resources use: https://api.cognitive.microsofttranslator.com Whereas regional resources must use the custom endpoint: https://<your-resource-name>.cognitiveservices.azure.com

Check authentication headers: Required header: Ocp-Apim-Subscription-Key: <your-key> For regional or multi‑service Translator resources, you must also include: Ocp-Apim-Subscription-Region: <your-resource-region> This header is optional for global Translator resources.

Validate active key: Navigate to Translator resource → Keys and Endpoint in Azure portal and ensure the key in use hasn’t been regenerated. You may also regenerate one of the keys and update your application.

• Review resource/subscription state: Confirm the Azure subscription is active, and the Translator resource hasn’t been deleted or recreated (which would invalidate previously used keys).

If the issue persists, please capture the exact timestamp of failure along with the X-RequestId response header for further backend investigation and share it in Private message.

Reference: Translator Authentication – https://dotnet.territoriali.olinfo.it/azure/ai-services/translator/text-translation/reference/authentication

A 401 Unauthorized on Azure Text Translation almost always indicates an authentication problem, even if the key and endpoint were working before.

Use these steps to troubleshoot:

1. Verify the subscription key
   • Go to the Translator resource in the Azure portal.
   • Open Keys and Endpoint.
   • Copy the current key and ensure the request header uses:
     • Ocp-Apim-Subscription-Key: <exact key value>
   • If using environment variables or app settings, confirm they were not changed or rotated.
2. Confirm the endpoint and region
   • From Keys and Endpoint, confirm the endpoint and region of the resource.
   • For a global free-tier resource, ensure:
     • The base URL matches the resource endpoint.
     • If specifying Ocp-Apim-Subscription-Region, its value matches the resource region. For a global resource this header is optional, but if present it must be correct.
3. Check if the resource or subscription changed
   • Confirm the Azure subscription is still active.
   • Confirm the Translator resource still exists and is not deleted or moved.
   • If the free-tier quota was exhausted and the resource was changed or recreated, make sure the code is using the new key.
4. Validate with the Try It tool
   • Since the Try It tool also fails, this strongly indicates an issue with the resource or subscription, not the client code.
   • After confirming keys and subscription status, regenerate a key in Keys and Endpoint, update the Try It tool and application with the new key, and test again.
5. Check service limits and quotas
   • If the issue persists but the status changes to 403, check whether the free-tier limits have been exceeded. For text translation limits, see Service limits - Translator.
6. Inspect HTTP responses and logs
   • Capture the full HTTP response, including headers and any JSON error body.
   • If using the .NET client library, wrap calls in a try/catch for RequestFailedException and log the details, including client request ID, as shown in the SDK troubleshooting guidance.

If, after confirming the key, endpoint, region, and subscription status, 401 continues from both code and the Try It tool, collect the exact time of failure and the X-RequestId response header and contact Azure support.

References:

• What is Azure Text translation in Foundry Tools?
• Azure Translator in Foundry Tools response codes and messages
• Azure Translator in Foundry Tools 3.0: Translate
• Azure Text Translation client library for .NET - version 1.0.0
• Azure resources for Translator