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Amazon Bedrock (Runtime API) error

Amazon Bedrock 400 IncompleteSignature: what it means and how to fix it

Error message
400 IncompleteSignature

Retry? Not statedLast verified 2 documented fixes1 source

What it means

The request signature does not conform to AWS standards.

Causes

  • AWS SDK version that does not support Amazon Bedrock
  • Misconfigured access key ID or secret key
  • Incorrect manual signature calculation

How to fix it

  1. Fix 1.

    Make sure you are using an AWS SDK version that supports Amazon Bedrock.

  2. Fix 2.

    Verify that your AWS access key ID and secret key are correctly configured; if signing manually, double-check your signature calculation.

More Amazon Bedrock errors

All 22 Amazon Bedrock errors

HTTP 400 at other providers

Compare 400 across providers

FAQ

What does the Amazon Bedrock error "400 IncompleteSignature" mean?

The request signature does not conform to AWS standards.

How do I fix Amazon Bedrock "400 IncompleteSignature"?

There are 2 documented fixes. Start with the first: Make sure you are using an AWS SDK version that supports Amazon Bedrock.

Should I retry Amazon Bedrock "400 IncompleteSignature"?

Not stated. The official docs do not say whether this error is retryable.

Which other AI APIs return HTTP 400?

Per their official error docs: Anthropic API (400 invalid_request_error; 400 invalid_request_error (spend limit reached)), Azure OpenAI (400 Bad Request; 400 content_filter), Cohere API (400 Bad Request; 400 Bad Request (too many tokens)), DeepSeek API (400 - Invalid Format), Gemini API (400 invalid_request; 400 failed_precondition; 400 parameter_unknown; 400 INVALID_ARGUMENT; 400 FAILED_PRECONDITION), Groq API (400 Bad Request), Mistral API (400 Bad request), OpenAI API (400 invalid_request_error (Invalid service_tier argument); 400 BadRequestError), OpenRouter (400 invalid_request; 400 invalid_prompt; 400 context_length_exceeded; 400 max_tokens_exceeded; 400 token_limit_exceeded; 400 string_too_long; 400 invalid_image; 400 image_too_large; 400 image_too_small; 400 unsupported_image_format; 400 image_download_failed), Vertex AI (400 INVALID_ARGUMENT / FAILED_PRECONDITION), xAI API (400 Bad Request).

Sources

Last verified against 1 source: Amazon Bedrock's official docs and official SDK repositories.

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