continuedev/continue · error · Error

Malformed JSON received from Bedrock: ${decoded}

Error message

Malformed JSON received from Bedrock: ${decoded}

What it means

Thrown while streaming a completion from Bedrock when a decoded response chunk fails JSON.parse or does not contain the expected outputs[0].text shape. The full offending payload is included in the message. It indicates the invoke-model-with-response-stream body could not be parsed as a valid Bedrock completion event.

Source

Thrown at core/llm/llms/BedrockImport.ts:62

        sessionToken: credentials.sessionToken || "",
      },
    });

    const input = this._generateInvokeModelCommandInput(prompt, options);
    const command = new InvokeModelWithResponseStreamCommand(input);
    const response = await client.send(command, { abortSignal: signal });

    if (response.body) {
      for await (const item of response.body) {
        const decoder = new TextDecoder();
        const decoded = decoder.decode(item.chunk?.bytes);
        try {
          const chunk = JSON.parse(decoded);
          if (chunk.outputs[0].text) {
            yield chunk.outputs[0].text;
          }
        } catch (e) {
          throw new Error(`Malformed JSON received from Bedrock: ${decoded}`);
        }
      }
    }
  }

  private _generateInvokeModelCommandInput(
    prompt: string,
    options: CompletionOptions,
  ): any {
    const payload = {
      prompt: prompt,
    };

    return {
      body: JSON.stringify(payload),
      modelId: this.modelArn,
      accept: "application/json",
      contentType: "application/json",

View on GitHub (pinned to 5522c6f44c)

Solutions

1. Inspect the ${decoded} payload in the message: an error JSON reveals the real cause (throttling, access denied)
2. Verify the modelId matches a model that supports invoke-model-with-response-stream in your region
3. Disable request/response compression or proxy buffering that could corrupt chunked SSE bytes
4. Retry the request: transient truncation usually succeeds on a second attempt

try {
  for await (const t of llm.streamComplete(prompt)) yield t;
} catch (e) {
  if (e instanceof Error && e.message.startsWith('Malformed JSON received from Bedrock')) {
    return retryStream(); // transient truncation often clears
  }
  throw e;
}

When it happens

Trigger: Calling _streamComplete where Bedrock returns an error event, a partial/garbled event body (network truncation, proxy buffering), a model whose stream payload schema differs (missing outputs array), or a modelId that routes to a non-converse API with mismatched response format.

Common situations: Using a Bedrock model whose streaming format changed (e.g. new foundation model versions), a corporate proxy mangling chunked responses, or streaming with on-demand throughput dropping mid-stream.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• No stream received from Bedrock API
• AWS Bedrock stream error (${(error as any).code}): ${error.m
• AWS Bedrock rerank error (${(error as any).code}): ${error.m
• Error in BedrockReranker.rerank: ${error.message}
• Error in BedrockReranker.rerank: Unknown error occurred

AI-assisted analysis of continuedev/continue@5522c6f44c (2026-08-27). Data as JSON: /api/errors/881f9fd7ab26a79f. Report an issue: GitHub.