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ModelRefusalError — the OpenAI Agents SDK’s exception for a refusal that ends a run

agents.exceptions.ModelRefusalError: Model refused to produce output: <refusal>

(Our rendering of the message the class builds, with the refusal text left as a placeholder.)

This error is the SDK reporting that the model’s last message in a turn was a refusal and that there was nothing else in the turn to carry on with. The text after the colon is the refusal text: the model’s own, passed through, except on one path shown below where the SDK writes it. This page is about what the SDK does with that refusal: the class, the check in the runner that raises it, the one hook that can turn it into an output instead, and what your code gets when it is raised. It says nothing about why a model refuses. Every claim about the library below is read off the Python source of openai-agents-python at release tag v0.23.1, fetched on 10 October 2026, with the address of each quoted line given; where we draw a conclusion from those lines rather than quote them, we say so.

The class

Defined in src/agents/exceptions.py (exceptions.py, lines 466–474):

class ModelRefusalError(AgentsException): """Exception raised when the model refuses to produce the requested output.""" refusal: str """The refusal text returned by the model.""" def __init__(self, refusal: str): self.refusal = refusal super().__init__(f"Model refused to produce output: {refusal}")

One field, one constructor argument, and a message built from it. The class defines no __str__ of its own, so its string form is that message, and e.refusal is the same text without the prefix (our reading).

Its parent is AgentsException(Exception), “Base class for all exceptions in the Agents SDK.”, which sets a run_data attribute to None in its constructor (exceptions.py, lines 434–441). So except AgentsException catches it (our reading of the class line).

Where it is raised

There is one place in the files we read that constructs it: the runner’s turn resolution, in src/agents/run_internal/turn_resolution.py. After tool results, handoffs and tool-produced final outputs have been dealt with, it takes the refusal from the last message item of the turn (run_internal/turn_resolution.py, line 964):

refusal = ItemHelpers.extract_refusal(message_items[-1].raw_item) if message_items else None

and checks it only when the turn has nothing left to do (run_internal/turn_resolution.py, lines 969–975):

if not processed_response.has_tools_or_approvals_to_run(): has_tool_activity_without_message = not message_items and bool( processed_response.tools_used or skipped_raw_item_ids ) if not has_tool_activity_without_message: if refusal: refusal_error = ModelRefusalError(refusal)

So a refusal is not raised while the same turn still has tool calls or approvals to run, nor when the turn had tool activity but no message (our reading of the two conditions). It comes before the structured-output branch, if output_schema is not None and not output_schema.is_plain_text(): (line 1010), so it applies whatever the agent’s output type is, plain text included (our reading of the order).

Which response content counts as a refusal: ItemHelpers.extract_refusal reads it from the message item’s raw_item. For a Chat Completions model the SDK’s converter adds the message’s refusal field to that item as a ResponseOutputRefusal content part (models/chatcmpl_converter.py, lines 229–231). The Chat Completions model class also makes one itself, for a filtered reply that arrived empty (models/openai_chatcompletions.py, lines 315–326):

# Some providers signal a filtered non-streaming completion only through # finish_reason="content_filter" and an otherwise empty message. Preserve # that terminal signal as a refusal instead of returning an empty output. if ( message is not None and first_choice is not None and first_choice.finish_reason == "content_filter" and not message.content and not message.refusal and not message.tool_calls ): message.refusal = "Response withheld by the provider's content filter."

So on that path the message after the colon can be Response withheld by the provider's content filter., which is the SDK’s text and not the model’s (our reading). The lines right after it handle the empty finish_reason="length" case the other way: they raise ModelBehaviorError, “rather than manufacturing a refusal that would route through model_refusal handlers” (lines 328–343).

What can turn it into an output

Runner.run takes an error_handlers argument (run.py, line 270):

error_handlers: RunErrorHandlers[TContext] | None = None,

described in its docstring as “Error handlers keyed by error kind.” (line 306). The refusal is offered to them before anything is raised (run_internal/turn_resolution.py, lines 982–990):

handler_result = await resolve_run_error_handler_result( error_handlers=error_handlers, error_kind="model_refusal", error=refusal_error, context_wrapper=context_wrapper, run_data=run_error_data, ) if handler_result is None: raise refusal_error

If the handler result is not None, its final_output is checked against the agent with validate_handler_final_output, appended to the history as a message when include_in_history is set, and the run finishes with it as the final output (lines 992–1009). So the key to register is the error kind "model_refusal" (our inference from error_kind="model_refusal"; we did not read the definition of RunErrorHandlers in this run). There is no retry in lines 964–1009: the handler or the raise are the only two ways out of that block (our reading). We found no model setting in the files we read that turns the check off.

What the caller sees

The exception leaves the turn as itself. Around the run, the runner catches it, and because it is an AgentsException, attaches the run so far to it before re-raising it (run.py, lines 2184–2186):

if isinstance(exc, AgentsException): _clear_data_redacted_error_traceback(exc) exc.run_data = RunErrorDetails(

followed by a bare raise (line 2197). The RunErrorDetails carries input, new_items, raw_responses, last_agent, context_wrapper and the guardrail results (lines 2186–2196). So you catch the same ModelRefusalError object, with .refusal and a filled .run_data, and e.run_data.raw_responses holds the model responses of the run (our reading). The streamed path does the same in run_internal/run_loop.py (lines 2008–2026). Both skip it when the error’s data has been redacted (the _is_error_data_redacted branch), in which case run_data may stay None (our reading).

What to do

from agents.exceptions import ModelRefusalError try: result = await Runner.run(agent, prompt) except ModelRefusalError as e: log.warning('refused: %s', e.refusal) if e.run_data is not None: last = e.run_data.last_agent raise

(Our sketch, built from the class, field and attribute names above. We did not read the Agent or RunErrorDetails classes themselves in this run.)

• Read e.refusal first. If it is the content-filter sentence quoted above, the SDK made it from an empty filtered Chat Completions reply; otherwise it is the model’s own refusal text (our reading).
• Decide whether a refusal is an error for you. If your caller can live with a fallback answer, register a "model_refusal" handler on Runner.run and return an output your agent’s output type accepts; otherwise catch the class and fail the request (our reading).
• Do not catch it as ModelBehaviorError. They are separate subclasses of AgentsException; catch ModelRefusalError, or AgentsException if you handle the SDK’s errors together.
• Keep run_data in your logs. It holds what the run produced before the refusal, which is what you need to reproduce it (our reading).

The thing worth keeping even if you never see this class again: a refusal with nothing left to run ends the run as an exception, unless a "model_refusal" handler hands back an output first (our reading).

What is behind this site

The short version: ModelRefusalError is the OpenAI Agents SDK’s AgentsException for a turn whose last message is a refusal and that has no tools or approvals left to run. It carries refusal, and its message is Model refused to produce output: followed by that text. It is raised in turn_resolution.py unless an error handler for "model_refusal" returns a result, and it reaches you with run_data attached.

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