Invalid client identifier {0} when trying oauth2/token

API Platform
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2

Dear @Howard_Lai

Thank you for query on the NHSE API developer community and apologies for the delayed response.
Please see the below forum posts for information which provides some guidance on this error:

Invalid client identifier when trying to authenticate for Application-restricted RESTful APIs sandbox environments - API Platform - NHS England Developer Community

e-RS FHIR API - Invalid Client Id - PTL INT - API Platform - NHS England Developer Community

If you have reviewed an verified all the actions in the above forum posts and still get Invalid client identifier, please raise a ticket via the NHS England Developer Help & Support / ServiceNow Customer Service Portal - Customer Support and include for each environment:

  • Application names and dev/int/sandbox Application IDs
  • The dev/int/sandbox API key you’re using (first/last 4 chars only in the ticket)
  • A redacted sample JWT payload (header + body, without signature)
  • The exact cURL or HTTP request you are sending (with secrets removed)
  • Approximate timestamp of a failing call:

Thanks,

NHS England API Platform team

Please note: The API Platform team can only address queries relevant to the NHS England API Platform, including security, rate limiting, logging, monitoring and alerting. For any API, CIS2, NHS Login specific queries, please reach out to the relevant API / Service teams.