Merge 3bde35d0e0 into a2c814654e

litellm/llms/vertex_ai/gemini/vertex_and_google_ai_studio_gemini.py

@@ -309,8 +309,6 @@ class VertexGeminiConfig(VertexAIBaseConfig, BaseConfig):
             "stop",
             "extra_headers",
             "seed",
-            "logprobs",
-            "top_logprobs",
             "modalities",
             "audio",
             "parallel_tool_calls",
@@ -323,6 +321,10 @@ class VertexGeminiConfig(VertexAIBaseConfig, BaseConfig):
         if self._supports_penalty_parameters(model):
             supported_params.extend(["frequency_penalty", "presence_penalty"])
 
+        # Gemini 3+ models do not support logprobs on Vertex AI
+        if not VertexGeminiConfig._is_gemini_3_or_newer(model):
+            supported_params.extend(["logprobs", "top_logprobs"])
+
         if supports_reasoning(model):
             supported_params.append("reasoning_effort")
             supported_params.append("thinking")

tests/test_litellm/llms/vertex_ai/gemini/test_vertex_and_google_ai_studio_gemini.py

@@ -5568,6 +5568,23 @@ class TestModelResponseIteratorCleanup:
         mock_response.aclose.assert_awaited_once()
 
 
+@pytest.mark.parametrize(
+    "model, expect_logprobs",
+    [
+        ("gemini-2.5-flash", True),
+        ("gemini-2.5-pro", True),
+        ("gemini-3.5-flash", False),
+        ("gemini-3-pro-preview", False),
+        ("gemini-3.1-flash", False),
+    ],
+)
+def test_logprobs_not_advertised_for_gemini_3(model, expect_logprobs):
+    """Gemini 3+ does not support logprobs on Vertex AI (#31600)."""
+    params = VertexGeminiConfig().get_supported_openai_params(model)
+    assert ("logprobs" in params) is expect_logprobs
+    assert ("top_logprobs" in params) is expect_logprobs
+
+
 def test_process_candidates_merges_thought_signatures_and_server_side_tools():
     """
     thought_signatures and server_side_tool_invocations must both survive in