diff --git a/endpoints/v2/manifest.py b/endpoints/v2/manifest.py
index c5ceafeac..13b637845 100644
--- a/endpoints/v2/manifest.py
+++ b/endpoints/v2/manifest.py
@@ -2,6 +2,7 @@ import logging
 import jwt.utils
 import json
 
+from peewee import IntegrityError
 from flask import make_response, request, url_for
 from collections import namedtuple, OrderedDict
 from jwkest.jws import SIGNER_ALGS, keyrep
@@ -404,7 +405,15 @@ def _generate_and_store_manifest(namespace, repo_name, tag_name):
 
   # Sign the manifest with our signing key.
   manifest = builder.build(docker_v2_signing_key)
-  manifest_row = model.tag.associate_generated_tag_manifest(namespace, repo_name, tag_name,
-                                                            manifest.digest, manifest.bytes)
 
-  return manifest_row
+  # Write the manifest to the DB. If an existing manifest already exists, return the
+  # one found.
+  try:
+    return model.tag.associate_generated_tag_manifest(namespace, repo_name, tag_name,
+                                                      manifest.digest, manifest.bytes)
+  except IntegrityError:
+    try:
+      return model.tag.load_tag_manifest(namespace, repo_name, tag_name)
+    except model.InvalidManifestException:
+      raise model.DataModelException('Could not load or generate manifest')
+