Google Workspace Migration

How to Fix MissingExchangeGuidException During Microsoft 365 Migration

Olivia Miller Oct 7, 2026 869 views

Question details

Users experience a migration failure when attempting to move from Google Workspace to Microsoft 365 due to a missing Exchange GUID property.

Fix MissingExchangeGuidException During Microsoft 365 Migration

Product: Microsoft 365
Device & OS: not provided
Scenario: Migrating mailboxes from Google Workspace to Microsoft 365 across different domains.
Observed behavior: The migration fails, throwing a MissingExchangeGuidException error because the target user object does not contain a valid ExchangeGuid property.

Before you start

Ensure you have Exchange Administrator permissions in your Microsoft 365 tenant and access to the Exchange Online PowerShell module before attempting to modify user attributes.

Solution 1Recommended

Verify Environment and Synchronize the Exchange GUID

Identify your Exchange environment and manually sync or assign the missing Exchange GUID using PowerShell to allow the migration to proceed.

This error is most common in Hybrid Exchange environments where the on-premises Exchange GUID has not successfully synchronized to the cloud.

You must first identify if your environment is cloud-only or hybrid, and then locate and apply the correct GUID.

Determine environment type

Check your Microsoft 365 admin center to confirm whether your organization utilizes a cloud-only, hybrid, or on-premises Exchange setup.

Connect to PowerShell

Open PowerShell as an Administrator and connect to the Exchange Online module using your admin credentials.

Check current GUID

Run the command 'Get-Mailbox -Identity <UserEmail> | Format-List ExchangeGuid' to verify if the GUID is blank or missing.

Sync the attribute

If you are in a hybrid environment, locate the GUID on the on-premises Exchange server using 'Get-RemoteMailbox', then force a synchronization to the cloud via Azure AD Connect.

Verify Environment and Synchronize the Exchange GUID

Administrative Support: If the issue persists in a complex hybrid environment, you may need to submit a private support request with Microsoft providing the complete migration error logs.

Solution 2

Apply Microsoft Community Remediation Scripts

Use official PowerShell commands documented by the Microsoft support community to fix known hybrid migration attribute errors.

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Frequently Asked Questions

What causes the MissingExchangeGuidException during migration?

This exception is triggered when the target user mailbox in Microsoft 365 lacks a valid Exchange GUID. The migration service requires this unique identifier to accurately map and transfer the email data from Google Workspace.

Is this error only found in hybrid environments?

While it is most common in hybrid setups where on-premises attributes fail to sync with Azure AD, it can occasionally happen in cloud-only environments if the user account was improperly provisioned before the migration.

How can I find a user's Exchange GUID?

You can find the Exchange GUID by connecting to Exchange Online PowerShell and running the command 'Get-Mailbox -Identity user@domain.com | Select ExchangeGuid'.

Migration & Recovery