fix: wrap sync instructor.to_json() in asyncio.to_thread for ato_json

Addresses Cursor Bugbot feedback: the function-calling path in ato_json
was still calling _create_instructor().to_json() synchronously, blocking
the event loop. Now wrapped in asyncio.to_thread() to offload the
blocking call to a separate thread.

Co-Authored-By: João <joao@crewai.com>

lib/crewai/src/crewai/task.py

@@ -47,7 +47,7 @@ from crewai.tasks.task_output import TaskOutput
 from crewai.tools.base_tool import BaseTool
 from crewai.utilities.config import process_config
 from crewai.utilities.constants import NOT_SPECIFIED, _NotSpecified
-from crewai.utilities.converter import Converter, convert_to_model
+from crewai.utilities.converter import Converter, aconvert_to_model, convert_to_model
 from crewai.utilities.file_store import (
     clear_task_files,
     get_all_files,
@@ -602,7 +602,7 @@ class Task(BaseModel):
                     json_output = None
             elif not self._guardrails and not self._guardrail:
                 raw = result
-                pydantic_output, json_output = self._export_output(result)
+                pydantic_output, json_output = await self._aexport_output(result)
             else:
                 raw = result
                 pydantic_output, json_output = None, None
@@ -1040,6 +1040,34 @@ Follow these guidelines:
 
         return pydantic_output, json_output
 
+    async def _aexport_output(
+        self, result: str
+    ) -> tuple[BaseModel | None, dict[str, Any] | None]:
+        """Async version of _export_output that uses async LLM calls."""
+        pydantic_output: BaseModel | None = None
+        json_output: dict[str, Any] | None = None
+
+        if self.output_pydantic or self.output_json:
+            model_output = await aconvert_to_model(
+                result,
+                self.output_pydantic,
+                self.output_json,
+                self.agent,
+                self.converter_cls,
+            )
+
+            if isinstance(model_output, BaseModel):
+                pydantic_output = model_output
+            elif isinstance(model_output, dict):
+                json_output = model_output
+            elif isinstance(model_output, str):
+                try:
+                    json_output = json.loads(model_output)
+                except json.JSONDecodeError:
+                    json_output = None
+
+        return pydantic_output, json_output
+
     def _get_output_format(self) -> OutputFormat:
         if self.output_json:
             return OutputFormat.JSON
@@ -1255,7 +1283,7 @@ Follow these guidelines:
 
                 if isinstance(guardrail_result.result, str):
                     task_output.raw = guardrail_result.result
-                    pydantic_output, json_output = self._export_output(
+                    pydantic_output, json_output = await self._aexport_output(
                         guardrail_result.result
                     )
                     task_output.pydantic = pydantic_output
@@ -1300,7 +1328,7 @@ Follow these guidelines:
                 tools=tools,
             )
 
-            pydantic_output, json_output = self._export_output(result)
+            pydantic_output, json_output = await self._aexport_output(result)
             task_output = TaskOutput(
                 name=self.name or self.description,
                 description=self.description,

lib/crewai/src/crewai/utilities/converter.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import asyncio
 import json
 import re
 from typing import TYPE_CHECKING, Any, Final, TypedDict
@@ -142,6 +143,103 @@ class Converter(OutputConverter):
                 return self.to_json(current_attempt + 1)
             return ConverterError(f"Failed to convert text into JSON, error: {e}.")
 
+    async def ato_pydantic(self, current_attempt: int = 1) -> BaseModel:
+        """Async version of to_pydantic. Convert text to pydantic without blocking the event loop.
+
+        Args:
+            current_attempt: The current attempt number for conversion retries.
+
+        Returns:
+            A Pydantic BaseModel instance.
+
+        Raises:
+            ConverterError: If conversion fails after maximum attempts.
+        """
+        try:
+            if self.llm.supports_function_calling():
+                response = await self.llm.acall(
+                    messages=[
+                        {"role": "system", "content": self.instructions},
+                        {"role": "user", "content": self.text},
+                    ],
+                    response_model=self.model,
+                )
+                if isinstance(response, BaseModel):
+                    result = response
+                else:
+                    result = self.model.model_validate_json(response)
+            else:
+                response = await self.llm.acall(
+                    [
+                        {"role": "system", "content": self.instructions},
+                        {"role": "user", "content": self.text},
+                    ]
+                )
+                try:
+                    result = self.model.model_validate_json(response)
+                except ValidationError:
+                    result = handle_partial_json(  # type: ignore[assignment]
+                        result=response,
+                        model=self.model,
+                        is_json_output=False,
+                        agent=None,
+                    )
+                    if not isinstance(result, BaseModel):
+                        if isinstance(result, dict):
+                            result = self.model.model_validate(result)
+                        elif isinstance(result, str):
+                            try:
+                                result = self.model.model_validate_json(result)
+                            except Exception as parse_err:
+                                raise ConverterError(
+                                    f"Failed to convert partial JSON result into Pydantic: {parse_err}"
+                                ) from parse_err
+                        else:
+                            raise ConverterError(
+                                "handle_partial_json returned an unexpected type."
+                            ) from None
+            return result
+        except ValidationError as e:
+            if current_attempt < self.max_attempts:
+                return await self.ato_pydantic(current_attempt + 1)
+            raise ConverterError(
+                f"Failed to convert text into a Pydantic model due to validation error: {e}"
+            ) from e
+        except Exception as e:
+            if current_attempt < self.max_attempts:
+                return await self.ato_pydantic(current_attempt + 1)
+            raise ConverterError(
+                f"Failed to convert text into a Pydantic model due to error: {e}"
+            ) from e
+
+    async def ato_json(self, current_attempt: int = 1) -> str | ConverterError | Any:
+        """Async version of to_json. Convert text to json without blocking the event loop.
+
+        Args:
+            current_attempt: The current attempt number for conversion retries.
+
+        Returns:
+            A JSON string or ConverterError if conversion fails.
+
+        Raises:
+            ConverterError: If conversion fails after maximum attempts.
+        """
+        try:
+            if self.llm.supports_function_calling():
+                return await asyncio.to_thread(self._create_instructor().to_json)
+            return json.dumps(
+                await self.llm.acall(
+                    [
+                        {"role": "system", "content": self.instructions},
+                        {"role": "user", "content": self.text},
+                    ]
+                )
+            )
+        except Exception as e:
+            if current_attempt < self.max_attempts:
+                return await self.ato_json(current_attempt + 1)
+            return ConverterError(f"Failed to convert text into JSON, error: {e}.")
+
     def _create_instructor(self) -> InternalInstructor[Any]:
         """Create an instructor."""
 
@@ -338,6 +436,176 @@ def convert_with_instructions(
     return exported_result
 
 
+async def aconvert_to_model(
+    result: str,
+    output_pydantic: type[BaseModel] | None,
+    output_json: type[BaseModel] | None,
+    agent: Agent | BaseAgent | None = None,
+    converter_cls: type[Converter] | None = None,
+) -> dict[str, Any] | BaseModel | str:
+    """Async version of convert_to_model. Convert a result string to a Pydantic model or JSON.
+
+    Uses async LLM calls to avoid blocking the event loop.
+
+    Args:
+        result: The result string to convert.
+        output_pydantic: The Pydantic model class to convert to.
+        output_json: The Pydantic model class to convert to JSON.
+        agent: The agent instance.
+        converter_cls: The converter class to use.
+
+    Returns:
+        The converted result as a dict, BaseModel, or original string.
+    """
+    model = output_pydantic or output_json
+    if model is None:
+        return result
+
+    if converter_cls:
+        return await aconvert_with_instructions(
+            result=result,
+            model=model,
+            is_json_output=bool(output_json),
+            agent=agent,
+            converter_cls=converter_cls,
+        )
+
+    try:
+        escaped_result = json.dumps(json.loads(result, strict=False))
+        return validate_model(
+            result=escaped_result, model=model, is_json_output=bool(output_json)
+        )
+    except json.JSONDecodeError:
+        return await ahandle_partial_json(
+            result=result,
+            model=model,
+            is_json_output=bool(output_json),
+            agent=agent,
+            converter_cls=converter_cls,
+        )
+
+    except ValidationError:
+        return await ahandle_partial_json(
+            result=result,
+            model=model,
+            is_json_output=bool(output_json),
+            agent=agent,
+            converter_cls=converter_cls,
+        )
+
+    except Exception as e:
+        if agent and getattr(agent, "verbose", True):
+            Printer().print(
+                content=f"Unexpected error during model conversion: {type(e).__name__}: {e}. Returning original result.",
+                color="red",
+            )
+        return result
+
+
+async def ahandle_partial_json(
+    result: str,
+    model: type[BaseModel],
+    is_json_output: bool,
+    agent: Agent | BaseAgent | None,
+    converter_cls: type[Converter] | None = None,
+) -> dict[str, Any] | BaseModel | str:
+    """Async version of handle_partial_json.
+
+    Args:
+        result: The result string to process.
+        model: The Pydantic model class to convert to.
+        is_json_output: Whether to return a dict (True) or Pydantic model (False).
+        agent: The agent instance.
+        converter_cls: The converter class to use.
+
+    Returns:
+        The converted result as a dict, BaseModel, or original string.
+    """
+    match = _JSON_PATTERN.search(result)
+    if match:
+        try:
+            exported_result = model.model_validate_json(match.group())
+            if is_json_output:
+                return exported_result.model_dump()
+            return exported_result
+        except json.JSONDecodeError:
+            pass
+        except ValidationError:
+            raise
+        except Exception as e:
+            if agent and getattr(agent, "verbose", True):
+                Printer().print(
+                    content=f"Unexpected error during partial JSON handling: {type(e).__name__}: {e}. Attempting alternative conversion method.",
+                    color="red",
+                )
+
+    return await aconvert_with_instructions(
+        result=result,
+        model=model,
+        is_json_output=is_json_output,
+        agent=agent,
+        converter_cls=converter_cls,
+    )
+
+
+async def aconvert_with_instructions(
+    result: str,
+    model: type[BaseModel],
+    is_json_output: bool,
+    agent: Agent | BaseAgent | None,
+    converter_cls: type[Converter] | None = None,
+) -> dict[str, Any] | BaseModel | str:
+    """Async version of convert_with_instructions.
+
+    Uses async LLM calls to avoid blocking the event loop.
+
+    Args:
+        result: The result string to convert.
+        model: The Pydantic model class to convert to.
+        is_json_output: Whether to return a dict (True) or Pydantic model (False).
+        agent: The agent instance.
+        converter_cls: The converter class to use.
+
+    Returns:
+        The converted result as a dict, BaseModel, or original string.
+
+    Raises:
+        TypeError: If neither agent nor converter_cls is provided.
+    """
+    if agent is None:
+        raise TypeError("Agent must be provided if converter_cls is not specified.")
+
+    llm = getattr(agent, "function_calling_llm", None) or agent.llm
+
+    if llm is None:
+        raise ValueError("Agent must have a valid LLM instance for conversion")
+
+    instructions = get_conversion_instructions(model=model, llm=llm)
+    converter = create_converter(
+        agent=agent,
+        converter_cls=converter_cls,
+        llm=llm,
+        text=result,
+        model=model,
+        instructions=instructions,
+    )
+    exported_result = (
+        await converter.ato_pydantic()
+        if not is_json_output
+        else await converter.ato_json()
+    )
+
+    if isinstance(exported_result, ConverterError):
+        if agent and getattr(agent, "verbose", True):
+            Printer().print(
+                content=f"Failed to convert result to model: {exported_result}",
+                color="red",
+            )
+        return result
+
+    return exported_result
+
+
 def get_conversion_instructions(
     model: type[BaseModel], llm: BaseLLM | LLM | str | Any
 ) -> str:

lib/crewai/tests/utilities/test_converter.py

@@ -8,6 +8,9 @@ from crewai.llm import LLM
 from crewai.utilities.converter import (
     Converter,
     ConverterError,
+    aconvert_to_model,
+    aconvert_with_instructions,
+    ahandle_partial_json,
     convert_to_model,
     convert_with_instructions,
     create_converter,
@@ -952,3 +955,351 @@ def test_internal_instructor_real_unsupported_provider() -> None:
 
     # Verify it's a configuration error about unsupported provider
     assert "Unsupported provider" in str(exc_info.value) or "unsupported" in str(exc_info.value).lower()
+
+
+# ============================================================
+# Async converter tests (issue #5230)
+# ============================================================
+
+@pytest.mark.asyncio
+async def test_ato_pydantic_with_function_calling() -> None:
+    """Test that ato_pydantic uses llm.acall instead of llm.call."""
+    from unittest.mock import AsyncMock
+
+    llm = Mock(spec=LLM)
+    llm.supports_function_calling.return_value = True
+    llm.acall = AsyncMock(return_value='{"name": "Eve", "age": 35}')
+
+    converter = Converter(
+        llm=llm,
+        text="Name: Eve, Age: 35",
+        model=SimpleModel,
+        instructions="Convert this text.",
+    )
+
+    output = await converter.ato_pydantic()
+
+    assert isinstance(output, SimpleModel)
+    assert output.name == "Eve"
+    assert output.age == 35
+
+    # Verify acall was used, not call
+    llm.acall.assert_called_once()
+    assert not hasattr(llm, "call") or not llm.call.called
+
+
+@pytest.mark.asyncio
+async def test_ato_pydantic_without_function_calling() -> None:
+    """Test that ato_pydantic uses llm.acall for non-function-calling LLMs."""
+    from unittest.mock import AsyncMock
+
+    llm = Mock(spec=LLM)
+    llm.supports_function_calling.return_value = False
+    llm.acall = AsyncMock(return_value='{"name": "Alice", "age": 30}')
+
+    converter = Converter(
+        llm=llm,
+        text="Name: Alice, Age: 30",
+        model=SimpleModel,
+        instructions="Convert this text.",
+    )
+
+    output = await converter.ato_pydantic()
+
+    assert isinstance(output, SimpleModel)
+    assert output.name == "Alice"
+    assert output.age == 30
+    llm.acall.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_ato_json_without_function_calling() -> None:
+    """Test that ato_json uses llm.acall instead of llm.call."""
+    from unittest.mock import AsyncMock
+
+    llm = Mock(spec=LLM)
+    llm.supports_function_calling.return_value = False
+    llm.acall = AsyncMock(return_value='{"name": "Bob", "age": 40}')
+
+    converter = Converter(
+        llm=llm,
+        text="Name: Bob, Age: 40",
+        model=SimpleModel,
+        instructions="Convert this text.",
+    )
+
+    output = await converter.ato_json()
+
+    assert isinstance(output, str)
+    llm.acall.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_ato_pydantic_retry_logic() -> None:
+    """Test that ato_pydantic retries on failure using acall."""
+    from unittest.mock import AsyncMock
+
+    llm = Mock(spec=LLM)
+    llm.supports_function_calling.return_value = False
+    llm.acall = AsyncMock(
+        side_effect=[
+            "Invalid JSON",
+            "Still invalid",
+            '{"name": "Retry Alice", "age": 30}',
+        ]
+    )
+
+    converter = Converter(
+        llm=llm,
+        text="Name: Retry Alice, Age: 30",
+        model=SimpleModel,
+        instructions="Convert this text.",
+        max_attempts=3,
+    )
+
+    output = await converter.ato_pydantic()
+
+    assert isinstance(output, SimpleModel)
+    assert output.name == "Retry Alice"
+    assert output.age == 30
+    assert llm.acall.call_count == 3
+
+
+@pytest.mark.asyncio
+async def test_ato_pydantic_error_after_max_attempts() -> None:
+    """Test that ato_pydantic raises ConverterError after max attempts."""
+    from unittest.mock import AsyncMock
+
+    llm = Mock(spec=LLM)
+    llm.supports_function_calling.return_value = False
+    llm.acall = AsyncMock(return_value="Invalid JSON")
+
+    converter = Converter(
+        llm=llm,
+        text="Name: Alice, Age: 30",
+        model=SimpleModel,
+        instructions="Convert this text.",
+        max_attempts=3,
+    )
+
+    with pytest.raises(ConverterError) as exc_info:
+        await converter.ato_pydantic()
+
+    assert "Failed to convert text into a Pydantic model" in str(exc_info.value)
+
+
+@pytest.mark.asyncio
+async def test_ato_json_retry_logic() -> None:
+    """Test that ato_json retries on failure using acall."""
+    from unittest.mock import AsyncMock
+
+    llm = Mock(spec=LLM)
+    llm.supports_function_calling.return_value = False
+    llm.acall = AsyncMock(
+        side_effect=[
+            Exception("LLM error"),
+            Exception("LLM error again"),
+            '{"name": "Bob", "age": 40}',
+        ]
+    )
+
+    converter = Converter(
+        llm=llm,
+        text="Name: Bob, Age: 40",
+        model=SimpleModel,
+        instructions="Convert this text.",
+        max_attempts=3,
+    )
+
+    output = await converter.ato_json()
+
+    assert isinstance(output, str)
+    assert llm.acall.call_count == 3
+
+
+@pytest.mark.asyncio
+async def test_aconvert_to_model_with_valid_json() -> None:
+    """Test aconvert_to_model with valid JSON (no LLM call needed)."""
+    result = '{"name": "John", "age": 30}'
+    output = await aconvert_to_model(result, SimpleModel, None, None)
+    assert isinstance(output, SimpleModel)
+    assert output.name == "John"
+    assert output.age == 30
+
+
+@pytest.mark.asyncio
+async def test_aconvert_to_model_with_no_model() -> None:
+    """Test aconvert_to_model returns plain text when no model specified."""
+    result = "Plain text"
+    output = await aconvert_to_model(result, None, None, None)
+    assert output == "Plain text"
+
+
+@pytest.mark.asyncio
+async def test_aconvert_to_model_with_json_output() -> None:
+    """Test aconvert_to_model returns dict when output_json is specified."""
+    result = '{"name": "John", "age": 30}'
+    output = await aconvert_to_model(result, None, SimpleModel, None)
+    assert isinstance(output, dict)
+    assert output == {"name": "John", "age": 30}
+
+
+@pytest.mark.asyncio
+async def test_aconvert_with_instructions_success() -> None:
+    """Test aconvert_with_instructions uses async converter methods."""
+    from unittest.mock import AsyncMock
+
+    mock_agent = Mock()
+    mock_agent.function_calling_llm = None
+    mock_agent.llm = Mock()
+
+    with patch("crewai.utilities.converter.create_converter") as mock_create_converter, \
+         patch("crewai.utilities.converter.get_conversion_instructions") as mock_get_instructions:
+        mock_get_instructions.return_value = "Instructions"
+        mock_converter = Mock()
+        mock_converter.ato_pydantic = AsyncMock(
+            return_value=SimpleModel(name="David", age=50)
+        )
+        mock_create_converter.return_value = mock_converter
+
+        result = "Some text to convert"
+        output = await aconvert_with_instructions(result, SimpleModel, False, mock_agent)
+
+        assert isinstance(output, SimpleModel)
+        assert output.name == "David"
+        assert output.age == 50
+        mock_converter.ato_pydantic.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_aconvert_with_instructions_json_output() -> None:
+    """Test aconvert_with_instructions uses ato_json for JSON output."""
+    from unittest.mock import AsyncMock
+
+    mock_agent = Mock()
+    mock_agent.function_calling_llm = None
+    mock_agent.llm = Mock()
+
+    with patch("crewai.utilities.converter.create_converter") as mock_create_converter, \
+         patch("crewai.utilities.converter.get_conversion_instructions") as mock_get_instructions:
+        mock_get_instructions.return_value = "Instructions"
+        mock_converter = Mock()
+        mock_converter.ato_json = AsyncMock(
+            return_value='{"name": "David", "age": 50}'
+        )
+        mock_create_converter.return_value = mock_converter
+
+        result = "Some text to convert"
+        output = await aconvert_with_instructions(result, SimpleModel, True, mock_agent)
+
+        assert output == '{"name": "David", "age": 50}'
+        mock_converter.ato_json.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_aconvert_with_instructions_failure() -> None:
+    """Test aconvert_with_instructions returns original result on ConverterError."""
+    from unittest.mock import AsyncMock
+
+    mock_agent = Mock()
+    mock_agent.function_calling_llm = None
+    mock_agent.llm = Mock()
+    mock_agent.verbose = True
+
+    with patch("crewai.utilities.converter.create_converter") as mock_create_converter, \
+         patch("crewai.utilities.converter.get_conversion_instructions") as mock_get_instructions:
+        mock_get_instructions.return_value = "Instructions"
+        mock_converter = Mock()
+        mock_converter.ato_pydantic = AsyncMock(
+            return_value=ConverterError("Conversion failed")
+        )
+        mock_create_converter.return_value = mock_converter
+
+        result = "Some text to convert"
+        with patch("crewai.utilities.converter.Printer") as mock_printer:
+            output = await aconvert_with_instructions(result, SimpleModel, False, mock_agent)
+            assert output == result
+            mock_printer.return_value.print.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_aconvert_with_instructions_no_agent() -> None:
+    """Test aconvert_with_instructions raises TypeError without agent."""
+    with pytest.raises(TypeError, match="Agent must be provided"):
+        await aconvert_with_instructions("text", SimpleModel, False, None)
+
+
+@pytest.mark.asyncio
+async def test_ahandle_partial_json_with_valid_partial() -> None:
+    """Test ahandle_partial_json with valid embedded JSON."""
+    result = 'Some text {"name": "Charlie", "age": 35} more text'
+    output = await ahandle_partial_json(result, SimpleModel, False, None)
+    assert isinstance(output, SimpleModel)
+    assert output.name == "Charlie"
+    assert output.age == 35
+
+
+@pytest.mark.asyncio
+async def test_ahandle_partial_json_delegates_to_aconvert_with_instructions() -> None:
+    """Test ahandle_partial_json delegates to aconvert_with_instructions for invalid JSON."""
+    from unittest.mock import AsyncMock
+
+    mock_agent = Mock()
+    mock_agent.function_calling_llm = None
+    mock_agent.llm = Mock()
+
+    result = "No valid JSON here"
+    with patch("crewai.utilities.converter.aconvert_with_instructions", new_callable=AsyncMock) as mock_aconvert:
+        mock_aconvert.return_value = "Converted result"
+        output = await ahandle_partial_json(result, SimpleModel, False, mock_agent)
+        assert output == "Converted result"
+        mock_aconvert.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_async_converter_does_not_call_sync_llm_call() -> None:
+    """Core test for issue #5230: verify that async converter path never uses sync llm.call()."""
+    from unittest.mock import AsyncMock
+
+    llm = Mock(spec=LLM)
+    llm.supports_function_calling.return_value = True
+    llm.acall = AsyncMock(return_value='{"name": "Test", "age": 25}')
+    llm.call = Mock(side_effect=AssertionError("sync llm.call() should not be called in async path"))
+
+    converter = Converter(
+        llm=llm,
+        text="Name: Test, Age: 25",
+        model=SimpleModel,
+        instructions="Convert this text.",
+    )
+
+    # ato_pydantic should use acall, never call
+    output = await converter.ato_pydantic()
+    assert isinstance(output, SimpleModel)
+    assert output.name == "Test"
+    assert output.age == 25
+    llm.acall.assert_called_once()
+    llm.call.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_async_converter_json_does_not_call_sync_llm_call() -> None:
+    """Verify ato_json for non-function-calling LLMs never uses sync llm.call()."""
+    from unittest.mock import AsyncMock
+
+    llm = Mock(spec=LLM)
+    llm.supports_function_calling.return_value = False
+    llm.acall = AsyncMock(return_value='{"name": "Test", "age": 25}')
+    llm.call = Mock(side_effect=AssertionError("sync llm.call() should not be called in async path"))
+
+    converter = Converter(
+        llm=llm,
+        text="Name: Test, Age: 25",
+        model=SimpleModel,
+        instructions="Convert this text.",
+    )
+
+    output = await converter.ato_json()
+    assert isinstance(output, str)
+    llm.acall.assert_called_once()
+    llm.call.assert_not_called()