Text from lib/googlecloudsdk/core/updater/update_manager.py.

Index: lib/googlecloudsdk/core/updater/local_state.py
--- lib/googlecloudsdk/core/updater/local_state.py.orig
+++ lib/googlecloudsdk/core/updater/local_state.py
@@ -54,10 +54,13 @@ class InvalidSDKRootError(Error):
 
   def __init__(self):
     super(InvalidSDKRootError, self).__init__(
-        'The components management action could not be performed because the '
-        'installation root of the Cloud SDK could not be located. '
-        'If you previously used the Cloud SDK installer, '
-        'you could re-install the SDK and retry again.')
+        'You cannot perform this action because this Cloud SDK '
+        'installation is managed by an external package manager.\n'
+        'Please consider using a separate installation of the Cloud '
+        'SDK created through the default mechanism described at: '
+        '{doc_url}\n'.format(
+            doc_url=config.INSTALLATION_CONFIG.documentation_url))
+
 
 
 class InvalidDownloadError(Error):
