bedrock_utils.py throwing an error on

[brnaba-aws]

Describe your environment

OS: Bedrock agentcore runtime
Python version: 3.13
Package version: 0.12.2

What happened?

It appears that in bedrock_utils.py at this line
the response doesn't contain any output and because of that, it is throwing an error:

See this log:

"exception.stacktrace": "Traceback (most recent call last):
  File \"/usr/local/lib/python3.13/site-packages/strands/event_loop/event_loop.py\", line 189, in event_loop_cycle
    async for tool_event in tool_events:
        yield tool_event
  File \"/usr/local/lib/python3.13/site-packages/strands/event_loop/event_loop.py\", line 531, in _handle_tool_execution
    async for event in events:
        yield event
  File \"/usr/local/lib/python3.13/site-packages/strands/event_loop/event_loop.py\", line 277, in recurse_event_loop
    async for event in events:
        yield event
  File \"/usr/local/lib/python3.13/site-packages/strands/event_loop/event_loop.py\", line 152, in event_loop_cycle
    async for model_event in model_events:
        if not isinstance(model_event, ModelStopReason):
            yield model_event
  File \"/usr/local/lib/python3.13/site-packages/strands/event_loop/event_loop.py\", line 396, in _handle_model_execution
    raise e
  File \"/usr/local/lib/python3.13/site-packages/strands/event_loop/event_loop.py\", line 337, in _handle_model_execution
    async for event in stream_messages(
    ...<7 lines>...
        yield event
  File \"/usr/local/lib/python3.13/site-packages/strands/event_loop/streaming.py\", line 457, in stream_messages
    async for event in process_stream(chunks, start_time):
        yield event
  File \"/usr/local/lib/python3.13/site-packages/strands/event_loop/streaming.py\", line 391, in process_stream
    async for chunk in chunks:
    ...<22 lines>...
            handle_redact_content(chunk[\"redactContent\"], state)
  File \"/usr/local/lib/python3.13/site-packages/strands/models/bedrock.py\", line 647, in stream
    await task
  File \"/usr/local/lib/python3.13/asyncio/threads.py\", line 25, in to_thread
    return await loop.run_in_executor(None, func_call)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File \"/usr/local/lib/python3.13/concurrent/futures/thread.py\", line 59, in run
    result = self.fn(*self.args, **self.kwargs)
  File \"/usr/local/lib/python3.13/site-packages/opentelemetry/instrumentation/threading/__init__.py\", line 171, in wrapped_func
    return original_func(*func_args, **func_kwargs)
  File \"/usr/local/lib/python3.13/site-packages/strands/models/bedrock.py\", line 686, in _stream
    for chunk in response[\"stream\"]:
                 ~~~~~~~~^^^^^^^^^^
  File \"/usr/local/lib/python3.13/site-packages/opentelemetry/instrumentation/botocore/extensions/bedrock_utils.py\", line 72, in __iter__
    self._process_event(event)
    ~~~~~~~~~~~~~~~~~~~^^^^^^^
  File \"/usr/local/lib/python3.13/site-packages/amazon/opentelemetry/distro/patches/_botocore_patches.py\", line 295, in patched_process_event
    old_process_event(self, event)
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
  File \"/usr/local/lib/python3.13/site-packages/opentelemetry/instrumentation/botocore/extensions/bedrock_utils.py\", line 137, in _process_event
    self._stream_done_callback(self._response)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
  File \"/usr/local/lib/python3.13/site-packages/opentelemetry/instrumentation/botocore/extensions/bedrock.py\", line 642, in stream_done_callback
    self._converse_on_success(
    ~~~~~~~~~~~~~~~~~~~~~~~~~^
        span, response, instrumentor_context, capture_content
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File \"/usr/local/lib/python3.13/site-packages/opentelemetry/instrumentation/botocore/extensions/bedrock.py\", line 503, in _converse_on_success
    choice = _Choice.from_converse(result, capture_content)
  File \"/usr/local/lib/python3.13/site-packages/opentelemetry/instrumentation/botocore/extensions/bedrock_utils.py\", line 493, in from_converse
    orig_message = response[\"output\"][\"message\"]
                   ~~~~~~~~^^^^^^^^^^
KeyError: 'output'
",

No checks are being made on the response content. Maybe good idea to have some sort of .get()??

Steps to Reproduce

Hard to do

Expected Result

shouldn't throw an error

Actual Result

the code crashes

Additional context

No response

Would you like to implement a fix?

None

Tip

_{React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it. Learn more here.}

[xrmx]

Thanks for reporting. Looking at the code this may happen when no messageStart event is received with role as assistant, not sure how how often does it happen but yeah makes sense to remove that assumption in the code consuming the result. If we can get a reproducer it would be great to have a recorded session so we can see what's actually going on and what role are we receiving or if we are getting a messageStart event at all.

[liustve]

Hi @xrmx , I was unable to reproduce this issue but I think the fix for this is relatively straightforward and shouldn't impact existing instrumentation behavior. Could you take a look? Thanks!

#3990