fix: set hard stop to avoid infinite loop in parsing errors

Author: greysonlalonde

lib/crewai/src/crewai/agents/crew_agent_executor.py

@@ -130,6 +130,7 @@ def __init__(
         self.messages: list[LLMMessage] = []
         self.iterations = 0
         self.log_error_after = 3
+        self.max_iterations_exceeded_count = 0
         if self.llm:
             # This may be mutating the shared llm object and needs further evaluation
             existing_stop = getattr(self.llm, "stop", [])
@@ -202,31 +203,33 @@ def _invoke_loop(self) -> AgentFinish:
         Returns:
             Final answer from the agent.
         """
-        formatted_answer = None
+        formatted_answer: AgentAction | AgentFinish | None = None
         while not isinstance(formatted_answer, AgentFinish):
             try:
                 if has_reached_max_iterations(self.iterations, self.max_iter):
+                    self.max_iterations_exceeded_count += 1
                     formatted_answer = handle_max_iterations_exceeded(
                         formatted_answer,
                         printer=self._printer,
                         i18n=self._i18n,
                         messages=self.messages,
                         llm=self.llm,
                         callbacks=self.callbacks,
+                        max_iterations_exceeded_count=self.max_iterations_exceeded_count,
                     )
+                else:
+                    enforce_rpm_limit(self.request_within_rpm_limit)
 
-                enforce_rpm_limit(self.request_within_rpm_limit)
-
-                answer = get_llm_response(
-                    llm=self.llm,
-                    messages=self.messages,
-                    callbacks=self.callbacks,
-                    printer=self._printer,
-                    from_task=self.task,
-                    from_agent=self.agent,
-                    response_model=self.response_model,
-                )
-                formatted_answer = process_llm_response(answer, self.use_stop_words)
+                    answer = get_llm_response(
+                        llm=self.llm,
+                        messages=self.messages,
+                        callbacks=self.callbacks,
+                        printer=self._printer,
+                        from_task=self.task,
+                        from_agent=self.agent,
+                        response_model=self.response_model,
+                    )
+                    formatted_answer = process_llm_response(answer, self.use_stop_words)
 
                 if isinstance(formatted_answer, AgentAction):
                     # Extract agent fingerprint if available

lib/crewai/src/crewai/utilities/agent_utils.py

@@ -127,6 +127,7 @@ def handle_max_iterations_exceeded(
     messages: list[LLMMessage],
     llm: LLM | BaseLLM,
     callbacks: list[TokenCalcHandler],
+    max_iterations_exceeded_count: int = 1,
 ) -> AgentAction | AgentFinish:
     """Handles the case when the maximum number of iterations is exceeded. Performs one more LLM call to get the final answer.
 
@@ -137,9 +138,11 @@ def handle_max_iterations_exceeded(
         messages: List of messages to send to the LLM.
         llm: The LLM instance to call.
         callbacks: List of callbacks for the LLM call.
+        max_iterations_exceeded_count: Number of times max iterations has been exceeded.
 
     Returns:
-        The final formatted answer after exceeding max iterations.
+        The final formatted answer after exceeding max iterations. Returns AgentAction on first
+        call to allow one more tool execution, then forces AgentFinish on subsequent calls.
     """
     printer.print(
         content="Maximum iterations reached. Requesting final answer.",
@@ -168,8 +171,23 @@ def handle_max_iterations_exceeded(
         )
         raise ValueError("Invalid response from LLM call - None or empty.")
 
-    # Return the formatted answer, regardless of its type
-    return format_answer(answer=answer)
+    try:
+        result = format_answer(answer=answer)
+        # Allow returning AgentAction on first two calls to execute tools
+        # On third call (count > 2), force AgentFinish to prevent infinite loop
+        if isinstance(result, AgentAction) and max_iterations_exceeded_count > 2:
+            return AgentFinish(
+                thought="Maximum iterations reached - forcing final answer",
+                output=answer,
+                text=answer,
+            )
+        return result
+    except OutputParserError:
+        return AgentFinish(
+            thought="Maximum iterations reached with parse error",
+            output=answer,
+            text=answer,
+        )
 
 
 def format_message_for_llm(

lib/crewai/tests/agents/test_agent.py

@@ -508,7 +508,7 @@ def counting_call(*args, **kwargs):
     assert isinstance(result, str)
     assert len(result) > 0
     assert call_count > 0
-    assert call_count == 3
+    assert call_count == 2
 
 
 @pytest.mark.vcr(filter_headers=["authorization"])