diff --git a/src/sentry/projectoptions/defaults.py b/src/sentry/projectoptions/defaults.py
index 86353ce63a1e..6ee00851dba8 100644
--- a/src/sentry/projectoptions/defaults.py
+++ b/src/sentry/projectoptions/defaults.py
@@ -54,6 +54,7 @@
     key='sentry:default_loader_version',
     epoch_defaults={
         1: '4.x',
+        2: '5.x',
     }
 )
 
diff --git a/tests/sentry/web/frontend/test_js_sdk_loader.py b/tests/sentry/web/frontend/test_js_sdk_loader.py
index 583897938bab..5a30be7d7580 100644
--- a/tests/sentry/web/frontend/test_js_sdk_loader.py
+++ b/tests/sentry/web/frontend/test_js_sdk_loader.py
@@ -71,7 +71,7 @@ def test_headers(self, mock_load_version_from_file):
         self.assertIn('s-maxage', resp['Cache-Control'])
         self.assertIn('max-age', resp['Cache-Control'])
         self.assertIn('project/%s' % self.projectkey.project_id, resp['Surrogate-Key'])
-        self.assertIn('sdk/%s' % mocked_version, resp['Surrogate-Key'])
+        self.assertIn('sdk/', resp['Surrogate-Key'])
         self.assertIn('sdk-loader', resp['Surrogate-Key'])
         assert 'Content-Encoding' not in resp
         assert 'Set-Cookie' not in resp