Qwen3 32B Thinking Model on Bedrock Truncates Output

This issue with truncated responses when using Qwen3 32B on Amazon Bedrock appears to be similar to problems reported with other models on the platform. When responses get interrupted mid-stream, it's typically related to how the response streaming is being handled.

There are a few potential causes and solutions to consider:

1. Response streaming implementation: The truncation might be happening because the response stream is being cut off prematurely. Amazon Bedrock provides an API called invoke_model_with_response_stream that's designed to handle streaming responses properly. If you're not already using this approach, implementing it could help prevent interruptions by processing the response as it's generated in chunks.

2. Token limits: While your specific issue doesn't appear to be a token limit problem (since the same model works fine on Ollama), it's worth checking if you're approaching any configured limits. Different models on Bedrock have different token constraints for output generation.

3. Model behavior differences: Some newer model versions on Bedrock have been reported to exhibit behavior where they include disclaimers about length constraints or abruptly end responses, even when token usage is well below configured limits. This has been observed particularly with Anthropic models but could potentially affect other models as well.

4. Client-side settings: Double-check your client-side configuration to ensure all parameters are correctly set, particularly any that might control response length or formatting.

For the most reliable solution, I'd recommend implementing the streaming approach using the Bedrock Runtime client and the invoke_model_with_response_stream command. This will allow you to process the response in chunks as it's generated, potentially avoiding the truncation issue you're experiencing.

If the problem persists after implementing streaming, it might be worth reaching out to AWS Support as this could be a specific issue with how the Qwen3 32B model is integrated with the Bedrock platform.
Sources
AWS bedrock - Response is getting interrupted in between. | AWS re:Post
Bedrock, Anthropic new Haiku/Sonnet 3.5 base models output length problem. | AWS re:Post