diff --git a/litellm/proxy/common_request_processing.py b/litellm/proxy/common_request_processing.py
index e7a08711eb1..c0ca45cb0da 100644
--- a/litellm/proxy/common_request_processing.py
+++ b/litellm/proxy/common_request_processing.py
@@ -1165,12 +1165,32 @@ async def _aclose_late_response(produced: Response) -> None:
             verbose_proxy_logger.debug("error closing relayed streaming generator: %s", exc)
 
 
-async def _relay_late_response(produced: Response) -> AsyncGenerator[bytes, None]:
+def _late_response_body(produced: object) -> bytes:
+    """Bytes for one SSE data frame.
+
+    A late payload may be a mapping, raw bytes or text, or a Response whose ``body`` is one of those.
+    """
+    payload: Final = (
+        produced if isinstance(produced, (bytes, bytearray, Mapping)) else getattr(produced, "body", produced)
+    )
+    if isinstance(payload, (bytes, bytearray)):
+        raw: Final = bytes(payload)
+        return raw or b"{}"
+    if isinstance(payload, str):
+        text: Final = payload.encode()
+        return text or b"{}"
+    if isinstance(payload, Mapping):
+        # orjson rejects mappingproxy and other non-dict mappings.
+        return orjson.dumps(dict(payload))
+    return b"{}"
+
+
+async def _relay_late_response(produced: object) -> AsyncGenerator[bytes, None]:
     """Replay a Response that was built after a keepalive had already opened the wire."""
     if not isinstance(produced, StreamingResponse):
         # The status line is already on the wire, so a non-streaming body, an error
         # body included, can only reach the client as an SSE frame.
-        yield b"data: " + (bytes(produced.body) or b"{}") + b"\n\n"
+        yield b"data: " + _late_response_body(produced) + b"\n\n"
         yield b"data: [DONE]\n\n"
         return
 
diff --git a/tests/test_litellm/proxy/common_utils/test_sse_keepalive.py b/tests/test_litellm/proxy/common_utils/test_sse_keepalive.py
index 228fd5bcae6..ca447b00538 100644
--- a/tests/test_litellm/proxy/common_utils/test_sse_keepalive.py
+++ b/tests/test_litellm/proxy/common_utils/test_sse_keepalive.py
@@ -3,7 +3,7 @@ from collections.abc import AsyncGenerator
 from typing import Final, cast
 
 import pytest
-from fastapi.responses import StreamingResponse
+from fastapi.responses import Response, StreamingResponse
 
 from litellm.proxy.common_request_processing import create_response
 from litellm.types.utils import ModelResponse
@@ -408,3 +408,72 @@ def test_ttft_interval_resolves_through_the_deployments_it_could_land_on(
     deployments, global_interval, expected, why
 ):
     assert resolve_ttft_keepalive_interval(deployments, global_interval) == expected, why
+
+
+@pytest.mark.asyncio
+async def test_relay_late_response_serializes_a_dict_payload_as_sse():
+    from litellm.proxy.common_request_processing import _relay_late_response
+
+    frames: Final = [chunk async for chunk in _relay_late_response({"error": {"message": "late"}})]
+
+    assert frames == [
+        b'data: {"error":{"message":"late"}}\n\n',
+        b"data: [DONE]\n\n",
+    ]
+
+
+@pytest.mark.asyncio
+async def test_relay_late_response_keeps_a_response_body():
+    from litellm.proxy.common_request_processing import _relay_late_response
+
+    frames: Final = [chunk async for chunk in _relay_late_response(Response(content=b'{"ok":true}'))]
+
+    assert frames == [
+        b'data: {"ok":true}\n\n',
+        b"data: [DONE]\n\n",
+    ]
+
+
+@pytest.mark.asyncio
+async def test_relay_late_response_serializes_a_dict_body_attribute():
+    from litellm.proxy.common_request_processing import _relay_late_response
+
+    class _DictBody:
+        body = {"ok": True}
+
+    frames: Final = [chunk async for chunk in _relay_late_response(_DictBody())]
+
+    assert frames[0] == b'data: {"ok":true}\n\n'
+    assert frames[1] == b"data: [DONE]\n\n"
+
+
+@pytest.mark.asyncio
+async def test_relay_late_response_encodes_a_string_payload():
+    from litellm.proxy.common_request_processing import _relay_late_response
+
+    frames: Final = [chunk async for chunk in _relay_late_response("late")]
+
+    assert frames == [b"data: late\n\n", b"data: [DONE]\n\n"]
+
+
+@pytest.mark.asyncio
+async def test_relay_late_response_uses_an_empty_object_for_an_unknown_payload():
+    from litellm.proxy.common_request_processing import _relay_late_response
+
+    class _NoBody:
+        pass
+
+    frames: Final = [chunk async for chunk in _relay_late_response(_NoBody())]
+
+    assert frames == [b"data: {}\n\n", b"data: [DONE]\n\n"]
+
+
+@pytest.mark.asyncio
+async def test_relay_late_response_serializes_a_mapping_proxy():
+    from types import MappingProxyType
+
+    from litellm.proxy.common_request_processing import _relay_late_response
+
+    frames: Final = [chunk async for chunk in _relay_late_response(MappingProxyType({"ok": True}))]
+
+    assert frames == [b'data: {"ok":true}\n\n', b"data: [DONE]\n\n"]