Troubleshoot a GSMME migration

When using G Suite Migration for Microsoft Exchange (GSMME), you may experience difficulty accessing users' Exchange mailboxes. GSMME's logs reveal generic issues, and the following troubleshooting tips show you how to identify the root cause of why an Exchange migration is failing. You can use this information to resolve your migration issue.

Before you contact support

Settings to verify before migration

Before starting your migration, make sure that Windows and Outlook have the latest Microsoft updates. We recommend that you sign in to Windows with the administrator account you'll be using for the migration. This will prevent login dialog boxes from popping up. Additionally, follow these tips to make sure you have the following set up correctly before running GSMME.

Outlook Profile

  • Create an Outlook profile for the admin user, which will be used for the migration. Select this profile in Specify a profile to use for migration. For more information, see the GSMME Admin Guide (PDF).
  • If, when setting up the admin Outlook profile, you get a Windows dialog box asking about auto-discovery, make sure you check Always allow before accepting.
  • When setting up the profile or opening Outlook, if you get a dialog box asking for a username and password, check the option to save credentials so you won't get asked again.
  • Before running the migration, follow these steps:
    1. Open the admin Outlook profile you created and open another user's mailbox.
    2. Navigate to their Inbox and make sure that you can read their messages. For more information, see Microsoft's instructions under "Add another person's mailbox to your profile".
  • If Windows or Outlook are not in English, try running the tool on a machine with English editions of Windows and Outlook. Also, make sure you're using Outlook 32-bit and not 64-bit.

Global Address List

  • While in the admin Outlook profile, try opening the Global Address List (GAL) and ensure that it loads completely.
  • Make sure that the admin account is a mailbox user and not hidden from the GAL.
  • Make sure that the admin profile is set not to use Cached Exchange mode. See Microsoft's documentation for more information.


  • In the Exchange username field in the CSV, enter just the usernames, without the domain name, for example: "username" and not "domain\username". See How to Create a CSV for GSMME for more information.
  • Make sure those users failing in your CSV don't have Out of Office status enabled.
Troubleshoot errors after migration

If you ran into some issues with your initial migration, follow the steps outlined above before performing the migration again. If the migration still doesn't work:

  • Try using the hostname of the Exchange server. If that doesn't work, try the IP address you used when you set up step 1 of GSMME.
  • In rare situations, Exchange users have resolved permission issues by also granting the admin to add Send/Receive permissions. Try toggling this setting in Microsoft Exchange (see Microsoft documentation for further assistance with this).

For additional help and resources, see the Troubleshooting article and GSMME error codes.

Contact support

If these troubleshooting steps don't resolve your issue, contact Google Cloud support with a ZIP file that includes all of the files found at C:\Users\username\AppData\Local\Google\Google Apps Migration\Tracing\ExchangeMigration. Also include the CSV file or files you used for the migration.

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