diff --git a/data/model/tag.py b/data/model/tag.py
index afc0b36cb..a392df2fd 100644
--- a/data/model/tag.py
+++ b/data/model/tag.py
@@ -223,7 +223,7 @@ def store_tag_manifest(namespace, repo_name, tag_name, docker_image_id, manifest
       return TagManifest.create(tag=tag, digest=manifest_digest, json_data=manifest_data)
 
 
-def _get_active_tag(namespace, repo_name, tag_name):
+def get_active_tag(namespace, repo_name, tag_name):
   return _tag_alive(RepositoryTag
                     .select()
                     .join(Image)
@@ -235,7 +235,7 @@ def _get_active_tag(namespace, repo_name, tag_name):
 
 def associate_generated_tag_manifest(namespace, repo_name, tag_name, manifest_digest,
                                      manifest_data):
-  tag = _get_active_tag(namespace, repo_name, tag_name)
+  tag = get_active_tag(namespace, repo_name, tag_name)
   return TagManifest.create(tag=tag, digest=manifest_digest, json_data=manifest_data)
 
 
diff --git a/endpoints/v2/manifest.py b/endpoints/v2/manifest.py
index c5ceafeac..00b7696aa 100644
--- a/endpoints/v2/manifest.py
+++ b/endpoints/v2/manifest.py
@@ -17,6 +17,7 @@ from endpoints.trackhelper import track_and_log
 from endpoints.notificationhelper import spawn_notification
 from digest import digest_tools
 from data import model
+from data.database import RepositoryTag
 
 
 logger = logging.getLogger(__name__)
@@ -217,6 +218,11 @@ def fetch_manifest_by_tagname(namespace, repo_name, manifest_ref):
   try:
     manifest = model.tag.load_tag_manifest(namespace, repo_name, manifest_ref)
   except model.InvalidManifestException:
+    try:
+      model.tag.get_active_tag(namespace, repo_name, manifest_ref)
+    except RepositoryTag.DoesNotExist:
+       raise ManifestUnknown()
+
     try:
       manifest = _generate_and_store_manifest(namespace, repo_name, manifest_ref)
     except model.DataModelException: