diff --git a/litellm/llms/anthropic/pass_through/adapters/transformation.py b/litellm/llms/anthropic/pass_through/adapters/transformation.py
index 022bc6337b5..4ad30bdcb92 100644
--- a/litellm/llms/anthropic/pass_through/adapters/transformation.py
+++ b/litellm/llms/anthropic/pass_through/adapters/transformation.py
@@ -636,6 +636,25 @@ class LiteLLMAnthropicMessagesAdapter:
                     assistant_message["reasoning_content"] = reasoning_content
                 new_messages.append(assistant_message)
 
+        has_conversational_input = any(m.get("role") != "system" for m in replayable_messages)
+        has_translated_conversation = any(m.get("role") != "system" for m in new_messages)
+        if has_conversational_input and not has_translated_conversation:
+            unrecognized_block_types = sorted(
+                {
+                    str(content.get("type"))
+                    for message in replayable_messages
+                    if message.get("role") != "system" and isinstance(message.get("content"), list)
+                    for content in message["content"]
+                    if isinstance(content, dict) and content.get("type") is not None
+                }
+            )
+            type_list = ", ".join(json.dumps(block_type) for block_type in unrecognized_block_types) or "unknown"
+            raise litellm.BadRequestError(
+                message=f"Anthropic pass-through: every message's content blocks were of unrecognized types ({type_list}), so translation produced an empty conversation. Refusing to dispatch a request with no messages.",
+                model=model or "",
+                llm_provider="anthropic",
+            )
+
         return new_messages
 
     @staticmethod
@@ -1763,4 +1782,4 @@ class LiteLLMAnthropicMessagesAdapter:
             type="content_block_delta",
             index=current_content_block_index,
             delta=content_block_delta,
-        )
+            )