How to Fix Exchange Hybrid MRS Migration Endpoint Errors
Question details
The user is unable to create an MRS migration endpoint using the Hybrid Configuration Wizard because Exchange Online cannot communicate with the on-premises Exchange MRS Proxy service.
- Product
- Microsoft Exchange
- Device & OS
- not provided
- Scenario
- Configuring a hybrid email migration environment between on-premises Exchange servers and Exchange Online.
- Observed behavior
- The Hybrid Configuration Wizard fails to create the MRS migration endpoint due to accessibility, authentication, or network configuration issues.
Ensure you have administrative access to both your on-premises Exchange environment and your Microsoft 365 tenant, and verify your external domain DNS settings are configured correctly.
Enable and Verify the MRS Proxy Endpoint
Ensure the Mailbox Replication Service (MRS) Proxy is enabled on all required servers and is externally accessible.
The Hybrid Configuration Wizard relies on the MRS Proxy service to move mailboxes between on-premises Exchange and Exchange Online. If this service is disabled or unreachable, the migration endpoint creation will fail.
Log in to the Exchange Admin Center (EAC) or use Exchange Management Shell to enable the MRS Proxy endpoint on all necessary Client Access servers.
Confirm that the external URL for Exchange Web Services (e.g., https://mail.example.com/ews/mrsproxy.svc) is publicly accessible from the internet.
Configure Firewalls and Certificates
Correct any network blocks or invalid certificates preventing Exchange Online from reaching the on-premises server.
Test Connectivity Using PowerShell
Use Exchange Management Shell commands to manually test the migration server's availability.
Manage Your Migration Planning Documents with WPS Office
While troubleshooting complex Exchange Server configurations requires specialized IT tools, planning and documenting your migration doesn't need expensive software. WPS Office is a lightweight, fully compatible alternative to Microsoft Office that lets you view, edit, and share migration plans, spreadsheets, and technical PDFs for free.
- 1. Download the installer: Visit the official WPS Office website to download the free installation package.
- 2. Install WPS Office: Run the setup file and follow the on-screen prompts to complete the installation.
- 3. Open your files: Launch WPS Office to immediately start editing your existing .docx, .xlsx, and .pptx files.
Frequently Asked Questions
Why does the Hybrid Configuration Wizard fail to connect to the MRS Proxy?
This typically occurs if the MRS Proxy service is disabled on your on-premises Client Access servers, if perimeter firewalls block port 443, or if your SSL certificate is untrusted or expired.
How can I verify if my MRS Proxy is enabled?
You can verify this by running 'Get-WebServicesVirtualDirectory | Select-Object Identity, MRSProxyEnabled' in the Exchange Management Shell. The value should return 'True'.
Do I need a public SSL certificate for the MRS migration endpoint?
Yes, Exchange Online requires a valid SSL certificate issued by a trusted third-party Certificate Authority to establish a secure connection with your on-premises servers.
Can incorrect Autodiscover settings cause migration endpoint errors?
Absolutely. The Hybrid Configuration Wizard uses Autodiscover to automatically locate the MRS proxy URL. If the external Autodiscover record is missing or pointing to the wrong server, the connection will fail.
