Fix #2549: Improve error handling for Ollama connection errors

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

src/crewai/llm.py

@@ -177,6 +177,10 @@ class LLM:
                 response = litellm.completion(**params)
                 return response["choices"][0]["message"]["content"]
             except Exception as e:
+                if "ollama" in str(self.model).lower() and ("connection refused" in str(e).lower() or "ollamaexception" in str(e).lower()):
+                    from crewai.utilities.exceptions.ollama_connection_exception import OllamaConnectionException
+                    raise OllamaConnectionException(str(e))
+                
                 if not LLMContextLengthExceededException(
                     str(e)
                 )._is_context_limit_error(str(e)):

src/crewai/utilities/exceptions/ollama_connection_exception.py

@@ -0,0 +1,18 @@
+class OllamaConnectionException(Exception):
+    """Exception raised when there's a connection issue with Ollama.
+    
+    This typically happens when Ollama is not running or is not accessible
+    at the expected URL.
+    """
+    
+    def __init__(self, error_message: str):
+        self.original_error_message = error_message
+        super().__init__(self._get_error_message(error_message))
+    
+    def _get_error_message(self, error_message: str):
+        return (
+            f"Failed to connect to Ollama. Original error: {error_message}\n"
+            "Please make sure Ollama is installed and running. "
+            "You can install Ollama from https://ollama.com/download and "
+            "start it by running 'ollama serve' in your terminal."
+        )

tests/test_ollama_connection.py

@@ -0,0 +1,17 @@
+import pytest
+from unittest.mock import patch, MagicMock
+from crewai.llm import LLM
+from crewai.utilities.exceptions.ollama_connection_exception import OllamaConnectionException
+
+class TestOllamaConnection:
+    def test_ollama_connection_error(self):
+        with patch('litellm.completion') as mock_completion:
+            mock_completion.side_effect = Exception("OllamaException - [Errno 111] Connection refused")
+            
+            llm = LLM(model="ollama/llama3")
+            
+            with pytest.raises(OllamaConnectionException) as exc_info:
+                llm.call([{"role": "user", "content": "Hello"}])
+            
+            assert "Failed to connect to Ollama" in str(exc_info.value)
+            assert "Please make sure Ollama is installed and running" in str(exc_info.value)