Error 10121 listing Workers dispatch namespaces

Developers Cloudflare Workers
1

For Workers & Pages, what is the name of the domain?

workers.dev

What is the error number?

10121

What is the error message?

HTTP 403 from GET /accounts/[redacted]/workers/dispatch/namespaces

What is the issue or error you’re encountering

A read-only request to list Workers dispatch namespaces returns HTTP 403 with error 10121, while other Workers read-only endpoints return HTTP 200. Does this indicate missing Workers for Platforms entitlement, or a token-scope or endpoint-access issue?

What steps have you taken to resolve the issue?

I used the same authenticated credentials to confirm that read-only requests for Workers scripts, settings, deployments, and versions succeed with HTTP 200. Only GET /accounts/[redacted]/workers/dispatch/namespaces returns HTTP 403 / error 10121.

Could someone please clarify:

  1. Does error 10121 conclusively mean Workers for Platforms is not enabled?
  2. Could hidden or legacy dispatch namespaces still be associated with the account?
  3. How can the complete dispatch-namespace inventory be verified read-only without purchasing or activating Workers for Platforms?

No deployment, namespace creation, plan activation, or configuration change has been attempted.

What are the steps to reproduce the issue?

  1. Authenticate to a Cloudflare account using credentials that can read Workers scripts, settings, deployments, and versions.
  2. Confirm those read-only Workers endpoints return HTTP 200.
  3. Send GET /accounts/[redacted]/workers/dispatch/namespaces using the same credentials.
  4. Observe HTTP 403 with error code 10121.