fix: download and base64-encode remote image URLs for ollama_chat

Ollama does not accept image URLs, so extract_images_from_message must send pure
base64. Remote http(s) image_url values were forwarded verbatim, making Ollama
fail with "illegal base64 data at input byte 5" (the ":" in "https:"). Download
and base64-encode them, mirroring the data:-URL handling fixed in #18465.

litellm/litellm_core_utils/prompt_templates/common_utils.py

@@ -1555,13 +1555,29 @@ def _extract_base64_data(image_url: str) -> str:
     return image_url
 
 
+def _extract_ollama_image_data(image_url: str) -> str:
+    """
+    Return pure base64 image data for providers like Ollama that do not accept URLs.
+
+    Remote http(s) URLs are downloaded and base64-encoded; data URLs have their base64
+    payload extracted; anything else is returned unchanged.
+    """
+    if image_url.startswith(("http://", "https://")):
+        from litellm.litellm_core_utils.prompt_templates.image_handling import (
+            convert_url_to_base64,
+        )
+
+        image_url = convert_url_to_base64(image_url)
+    return _extract_base64_data(image_url)
+
+
 def extract_images_from_message(message: AllMessageValues) -> List[str]:
     """
     Extract images from a message.
 
-    For data URLs (e.g., "data:image/png;base64,iVBOR..."), only the base64
-    data portion is extracted. This is required for providers like Ollama
-    that expect pure base64 data rather than full data URLs.
+    For data URLs (e.g., "data:image/png;base64,iVBOR..."), only the base64 data portion is
+    extracted, and remote http(s) URLs are downloaded and base64-encoded. This is required for
+    providers like Ollama that expect pure base64 data rather than URLs or full data URLs.
     """
     images = []
     message_content = message.get("content")
@@ -1570,9 +1586,9 @@ def extract_images_from_message(message: AllMessageValues) -> List[str]:
             image_url = m.get("image_url")
             if image_url:
                 if isinstance(image_url, str):
-                    images.append(_extract_base64_data(image_url))
+                    images.append(_extract_ollama_image_data(image_url))
                 elif isinstance(image_url, dict) and "url" in image_url:
-                    images.append(_extract_base64_data(image_url["url"]))
+                    images.append(_extract_ollama_image_data(image_url["url"]))
     return images
 
 

tests/test_litellm/litellm_core_utils/test_extract_base64_image.py

@@ -7,6 +7,8 @@ which fixes the Ollama error "illegal base64 data at input byte 4".
 Related issue: https://github.com/BerriAI/litellm/issues/18338
 """
 
+from unittest.mock import patch
+
 import pytest
 
 from litellm.litellm_core_utils.prompt_templates.common_utils import (
@@ -91,8 +93,12 @@ class TestExtractImagesFromMessage:
         result = extract_images_from_message(message)
         assert result == ["iVBORw0KGgo"]
 
-    def test_extract_from_message_with_regular_url(self):
-        """Test that regular URLs are preserved"""
+    def test_extract_from_message_with_remote_url_downloads_and_encodes(self):
+        """Remote http(s) URLs must be downloaded and base64-encoded (issue #30313).
+
+        Ollama does not accept URLs, so forwarding one verbatim made it fail with
+        "illegal base64 data at input byte 5".
+        """
         message = {
             "role": "user",
             "content": [
@@ -102,8 +108,14 @@ class TestExtractImagesFromMessage:
                 }
             ],
         }
-        result = extract_images_from_message(message)
-        assert result == ["https://example.com/image.png"]
+        with patch(
+            "litellm.litellm_core_utils.prompt_templates.image_handling.convert_url_to_base64",
+            return_value="data:image/png;base64,ZmV0Y2hlZA==",
+        ) as mock_convert:
+            result = extract_images_from_message(message)
+
+        mock_convert.assert_called_once_with("https://example.com/image.png")
+        assert result == ["ZmV0Y2hlZA=="]
 
     def test_extract_multiple_images(self):
         """Test extracting multiple images from a single message"""
@@ -124,11 +136,15 @@ class TestExtractImagesFromMessage:
                 },
             ],
         }
-        result = extract_images_from_message(message)
+        with patch(
+            "litellm.litellm_core_utils.prompt_templates.image_handling.convert_url_to_base64",
+            return_value="data:image/png;base64,image3base64",
+        ):
+            result = extract_images_from_message(message)
         assert result == [
             "image1base64",
             "image2base64",
-            "https://example.com/image3.png",
+            "image3base64",
         ]
 
     def test_empty_content(self):