fix: Sanitize empty text content blocks for databricks provider (#20384)

* fix(databricks): sanitize empty text content blocks for Anthropic Messages API

* test(databricks): add tests for empty content block sanitization

litellm/llms/databricks/chat/transformation.py

@@ -60,6 +60,38 @@ from ...anthropic.chat.transformation import AnthropicConfig
 from ...openai_like.chat.transformation import OpenAILikeChatConfig
 from ..common_utils import DatabricksBase, DatabricksException
 
+def _sanitize_empty_content(message_dict: dict) -> None:
+    """
+    Remove or filter content so empty text blocks are not sent.
+    Databricks Model Serving uses Anthropic Messages API spec and rejects empty text blocks.
+    """
+    content = message_dict.get("content")
+    if content is None:
+        message_dict.pop("content", None)
+        return
+    if isinstance(content, str):
+        if not content.strip():
+            message_dict.pop("content")
+        return
+    if isinstance(content, list):
+        if not content:
+            message_dict.pop("content")
+            return
+        filtered = [
+            block
+            for block in content
+            if not (
+                isinstance(block, dict)
+                and block.get("type") == "text"
+                and not (block.get("text") or "").strip()
+            )
+        ]
+        if not filtered:
+            message_dict.pop("content")
+        else:
+            message_dict["content"] = filtered
+
+
 if TYPE_CHECKING:
     from litellm.litellm_core_utils.litellm_logging import Logging as _LiteLLMLoggingObj
 
@@ -350,6 +382,7 @@ class DatabricksConfig(DatabricksBase, OpenAILikeChatConfig, AnthropicConfig):
             # Move message-level cache_control into a content block when content is a string.
             if "cache_control" in _message and isinstance(_message.get("content"), str):
                 _message = self._move_cache_control_into_string_content_block(_message)
+            _sanitize_empty_content(_message)
             new_messages.append(_message)
 
         if is_async:

tests/test_litellm/llms/databricks/chat/test_databricks_chat_transformation.py

@@ -13,6 +13,7 @@ from unittest.mock import MagicMock, patch
 from litellm.llms.databricks.chat.transformation import (
     DatabricksChatResponseIterator,
     DatabricksConfig,
+    _sanitize_empty_content,
 )
 
 
@@ -215,3 +216,45 @@ def test_chunk_parser_with_citation():
             "end_char_index": 50,
         }
     }
+
+
+def test_sanitize_empty_content_pops_none():
+    message = {"role": "user", "content": None}
+    _sanitize_empty_content(message)
+    assert "content" not in message
+
+
+def test_sanitize_empty_content_pops_empty_string():
+    message = {"role": "user", "content": ""}
+    _sanitize_empty_content(message)
+    assert "content" not in message
+
+
+def test_sanitize_empty_content_pops_single_empty_text_block():
+    message = {"role": "user", "content": [{"type": "text", "text": ""}]}
+    _sanitize_empty_content(message)
+    assert "content" not in message
+
+
+def test_sanitize_empty_content_filters_empty_blocks_keeps_non_empty():
+    message = {
+        "role": "user",
+        "content": [
+            {"type": "text", "text": ""},
+            {"type": "text", "text": "Hello"},
+            {"type": "text", "text": "  "},
+        ],
+    }
+    _sanitize_empty_content(message)
+    assert message["content"] == [{"type": "text", "text": "Hello"}]
+
+
+def test_transform_messages_sanitizes_empty_content():
+    config = DatabricksConfig()
+    messages = [
+        {"role": "user", "content": [{"type": "text", "text": ""}]},
+        {"role": "user", "content": "Hi"},
+    ]
+    result = config._transform_messages(messages=messages, model="databricks-claude", is_async=False)
+    assert "content" not in result[0]
+    assert result[1]["content"] == "Hi"