diff --git a/src/backend/core/api/viewsets.py b/src/backend/core/api/viewsets.py
index b5d4304af..a01e948a5 100644
--- a/src/backend/core/api/viewsets.py
+++ b/src/backend/core/api/viewsets.py
@@ -10,6 +10,7 @@ import logging
 import socket
 import uuid
 from collections import defaultdict
+from io import BytesIO
 from urllib.parse import unquote, urlencode, urlparse
 
 from django.conf import settings
@@ -35,6 +36,7 @@ import requests
 import rest_framework as drf
 import waffle
 from botocore.exceptions import ClientError
+from botocore.response import StreamingBody
 from csp.constants import NONE
 from csp.decorators import csp_update
 from lasuite.malware_detection import malware_detection
@@ -2143,7 +2145,9 @@ class DocumentViewSet(
                     return drf_response.Response(status=status.HTTP_304_NOT_MODIFIED)
                 case "NoSuchKey" | "404":
                     return StreamingHttpResponse(
-                        b"", content_type="text/plain", status=200
+                        content_stream(StreamingBody(BytesIO(b""), content_length=0)),
+                        content_type="text/plain",
+                        status=200,
                     )
                 case _:
                     raise
diff --git a/src/backend/core/tests/documents/test_api_documents_content_retrieve.py b/src/backend/core/tests/documents/test_api_documents_content_retrieve.py
index 59bd40f54..3d1ce1c3b 100644
--- a/src/backend/core/tests/documents/test_api_documents_content_retrieve.py
+++ b/src/backend/core/tests/documents/test_api_documents_content_retrieve.py
@@ -141,7 +141,7 @@ def test_api_documents_content_retrieve_nonexistent_document():
 
 
 def test_api_documents_content_retrieve_file_not_in_storage():
-    """Returns an empty string when the file does not exists on the storage."""
+    """Returns an empty string when the file does not exist on the storage."""
     user = factories.UserFactory()
     document = factories.DocumentFactory(link_reach="restricted")
     factories.UserDocumentAccessFactory(document=document, user=user, role="reader")
@@ -188,13 +188,48 @@ async def test_api_documents_content_retrieve_async(monkeypatch):
 
     assert response.status_code == status.HTTP_200_OK
     # Wait for the streaming content to be fully received => async iterator -> list
-    # This fails it the streaming is not an async generator
+    # This fails if the streaming is not an async generator
     response_content = b"".join(
         [content async for content in response.streaming_content]
     ).decode("utf-8")
     assert response_content == factories.YDOC_HELLO_WORLD_BASE64
 
 
+@pytest.mark.django_db(transaction=True)
+@pytest.mark.asyncio(loop_scope="function")
+async def test_api_documents_content_retrieve_file_not_in_storage_async(monkeypatch):
+    """Returns an empty string when the file does not exist on the storage."""
+    monkeypatch.setenv("PYTHON_SERVER_MODE", "async")
+
+    user = await sync_to_async(factories.UserFactory)()
+    document = await sync_to_async(factories.DocumentFactory)(link_reach="restricted")
+    await sync_to_async(factories.UserDocumentAccessFactory)(
+        document=document, user=user, role="reader"
+    )
+
+    client = APIClient()
+    await client.aforce_login(user)
+
+    await sync_to_async(default_storage.delete)(document.file_key)
+
+    assert not await sync_to_async(default_storage.exists)(document.file_key)
+
+    response = await sync_to_async(client.get)(
+        f"/api/v1.0/documents/{document.id!s}/content/"
+    )
+
+    assert response.status_code == status.HTTP_200_OK
+    # Wait for the streaming content to be fully received => async iterator -> list
+    # This fails if the streaming is not an async generator
+    assert b"".join([content async for content in response.streaming_content]) == b""
+    assert not response.get("Content-Length")
+    assert not response.get("ETag")
+    assert not response.get("Last-Modified")
+    assert not response.get("Cache-Control")
+
+    assert not await cache.aget(get_content_metadata_cache_key(document.id))
+
+
 def test_api_documents_content_retrieve_content_length_header():
     """The response includes the Content-Length header when available from storage."""
     user = factories.UserFactory()
diff --git a/src/backend/core/utils/s3_response_stream.py b/src/backend/core/utils/s3_response_stream.py
index a029a356a..ddf364f39 100644
--- a/src/backend/core/utils/s3_response_stream.py
+++ b/src/backend/core/utils/s3_response_stream.py
@@ -6,6 +6,15 @@ from asgiref.sync import sync_to_async
 from botocore.response import StreamingBody
 
 
+def _is_async_server():
+    """
+    Return whether the app runs as an ASGI application, based on the
+    PYTHON_SERVER_MODE environment variable (set in impress/asgi.py and
+    impress/wsgi.py).
+    """
+    return os.environ.get("PYTHON_SERVER_MODE", "sync") == "async"
+
+
 def sync_stream(body: StreamingBody):
     """Synchronous generator consuming s3 response body."""
     yield from body.iter_chunks()
@@ -35,6 +44,4 @@ def content_stream(body: StreamingBody):
     warning and be consumed synchronously, defeating the purpose of
     streaming.
     """
-    is_async_server = os.environ.get("PYTHON_SERVER_MODE", "sync") == "async"
-
-    return async_stream(body) if is_async_server else sync_stream(body)
+    return async_stream(body) if _is_async_server() else sync_stream(body)