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General

AWS request signature does not conform to standards

IncompleteSignature

AWS could not validate the request signature because the signing data is malformed, incomplete, or inconsistent with the expected AWS signing standard.

IncompleteSignatureauthentication

Observed message

IncompleteSignature

Why it happens

  • Custom signing logic generated an invalid or incomplete signature.
  • Credentials, headers, or canonical request elements do not match the signed request.
  • A proxy or middleware modified the request after it was signed.

How to fix it

  1. Use the official AWS SDK signing flow where possible.
  2. Check canonical headers, region, service name, and signing credentials.
  3. Ensure the request is not modified after signing.

Official reference

AWS Support API Reference: Common Errors

Related errors

AccessDeniedExceptionAWS API request failed with AccessDeniedExceptionUnrecognizedClientExceptionAWS did not recognize the client credentials in the requestNotAuthorizedAWS request failed with NotAuthorizedMissingAuthenticationTokenAWS request is missing an authentication token

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AWS IncompleteSignature: causes and fixes | Error Atlas