Veeam Support Knowledge Base
Veeam Backup for Microsoft 365 Restore Portal Error: "The server has rejected the client credentials"

Veeam Backup for Microsoft 365 Restore Portal Error: "The server has rejected the client credentials"

KB ID:	4292
Product:	Veeam Backup for Microsoft 365 \| 6.0 \| 7.0 \| 7a \| 8 \| 8.1
Published:	2022-03-24
Last Modified:	2025-03-28

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Challenge

When attempting to login to the Veeam Backup for Microsoft 365 Restore Portal, the following error occurs:

The server has rejected the client credentials.

Cause

At this time, there are two known scenarios that may cause this issue:

Scenario 1: Certificate not added to the Trusted Root Certification Authorities

When configuring the "Enable restore operator authentication with Microsoft credentials" feature, a certificate was selected from the Certificate Store, or a certificate was imported. However, that certificate was not added to the Trusted Root Certification Authorities.

Scenario 2: Updated Application certificate not in Azure Active Directory

The application certificate within the Restore Portal settings has been updated, but it has not been added to the application settings of Azure Active Directory.

Solution

Scenario 1: Certificate not added to the Trusted Root Certification Authorities

Make sure that the certificate is added to the Trusted Root Certification Authorities.

Reference: Authentication Settings

Scenario 2: Updated Application certificate not in Azure Active Directory

If the certificate is updated within Veeam Backup for Microsoft 365, it must also be added in the application settings through the Azure AD admin center.

Reference: Restore Portal Settings

More Information

If this issue persists, please create a Veeam Support Case.

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