We log search terms to improve our documentation. For more information, read our Privacy Policy.

Microsoft Connection Failures

Problem

When configuring Microsoft® as your mail provider, a Connection unsuccessful error message displays after you click Connect:

Connection unsuccessful. Please close this window and try again.

Cause

This error has two potential causes:

  • The Application (client) ID and Client Secret combination for your Microsoft Entra® ID (formerly Microsoft Azure®) app are invalid.
  • Your organization’s Microsoft Entra ID tenant restricts user consent for app permissions, which prevents WHMCS from completing the connection.

Solution

Invalid Application (Client) ID or Client Secret

Create a new app via the Microsoft Entra ID portal. Make certain to copy the Application (client) ID and Client Secret Value correctly.

For steps, see Use Microsoft for System Mail.

If your organization restricts users from consenting to app permissions, a tenant administrator must grant consent for the app’s required API permissions.

To do this:

  1. Go to the Microsoft Entra Portal and log in with an administrator account.
  2. In the left side menu, go to Entra ID > App registrations and select the app that you created for WHMCS.
  3. Under Manage, go to the API permissions menu.
  4. Confirm the list includes the required permissions. If it does not, add them.
  5. Click Grant admin consent for your organization.
Contact your Microsoft Entra ID administrator if you do not have access to grant admin consent.
troubleshooting troubleshooting-article microsoft-mail-provider

Last modified: 2026 July 22