Azure Speech Custom Keyword: OPTIONS preflight returns HTTP 302 to /Home/Error

Arie Smit 0 Reputation points
2026-09-21T12:03:32.68+00:00

I am unable to access Custom Keyword Projects in Azure Speech Studio.

When I open the Custom Keyword section, the Projects page does not load. Chrome reports a CORS error because the Custom Keyword API returns a redirect for the CORS preflight request.

The relevant request is:

OPTIONS https://northeurope.customkeyword.api.speech.microsoft.com/keywordspotting/v3.0-beta3/projects/locales

The response is:

HTTP/2 302 Found

Location: /Home/Error?aspxerrorpath=/keywordspotting/v3.0-beta3/projects/locales

Server: Microsoft-IIS/10.0

X-Powered-By: ASP.NET

Chrome reports:

Access to XMLHttpRequest at

'https://northeurope.customkeyword.api.speech.microsoft.com/keywordspotting/v3.0-beta3/projects/locales'

from origin 'https://speech.microsoft.com' has been blocked by CORS policy:

Response to preflight request doesn't pass access control check:

Redirect is not allowed for a preflight request.

The corresponding GET request also fails with:

GET https://northeurope.customkeyword.api.speech.microsoft.com/keywordspotting/v3.0-beta3/projects

net::ERR_FAILED

Testing performed

This is not limited to one existing Custom Keyword project or one Speech resource.

I have two Speech resources under the same Azure subscription:

  • Test1 — East US
  • Test2 — North Europe

Test1 was the original resource where I created an Advanced Custom Keyword model. The training took a very long time and subsequently Custom Keyword became inaccessible.

To rule out a problem with that resource/project, I created Test2" as a completely new Speech resource in North Europe and tried to open Custom Keyword without creating any project there.

The same problem occurs with Test2: the Custom Keyword Projects page cannot be opened and the API preflight request returns HTTP 302 to /Home/Error.

I have also tested this in Windows 11/Edge.

Could Microsoft please confirm whether there is currently a backend/service issue with the Azure Speech Custom Keyword API (customkeyword.api.speech.microsoft.com), specifically the v3.0-beta3 endpoints?

It appears that the server is returning an ASP.NET error redirect (302 /Home/Error) to an OPTIONS CORS preflight request. Because browsers do not follow redirects for CORS preflight requests, Speech Studio cannot access the Custom Keyword API.

Is this a known issue, or is there anything that can be done to restore access to Custom Keyword Projects?

I can provide additional F12 Network/Console information if required.

Azure Speech in Foundry Tools
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  1. Arie Smit 0 Reputation points
    2026-10-01T13:49:56.9233333+00:00

    It suddenly worked again after a week. Sometimes patience is a virtue.

    The wakeword creation failed but removed and try again :).

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  2. Arie Smit 0 Reputation points
    2026-10-01T13:49:29.1366667+00:00

    It suddenly worked again after a week. Sometimes patience is a virtue.

    The wakeword creation failed but removed and try again :).

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  3. Taz 10,126 Reputation points MVP Volunteer Moderator
    2026-09-21T18:12:48.7266667+00:00

    Hi Arie,

    Based on the behavior you described, this looks like a service-side issue rather than a problem with your Speech resources or browser.

    The key point is that the OPTIONS preflight is receiving a 302 redirect to /Home/Error. A CORS preflight is not expected to be redirected, so the browser blocks the request before Speech Studio can access the Custom Keyword API.

    Microsoft's documentation confirms that Custom Keyword projects are created and managed through Speech Studio, and the current service still supports this feature.

    Since you reproduced the same issue with a new Speech resource in another region, I would open an Azure Support request and provide the failing OPTIONS request, 302 response, region, and timestamp. This should allow the Speech team to check the backend service.

    I would not spend more time recreating Speech resources or changing browser CORS settings until Microsoft confirms the service-side issue.

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