Reauthorizing Veeam Data Cloud for Microsoft 365

You may need to reauthorize Veeam Data Cloud access to your Microsoft 365 tenant. This may be required in the following cases:

• If you have accidentally removed authorization for Veeam Data Cloud to access your Microsoft 365 data.
• If you see the following error message in your backup logs: The identity of the calling application could not be established.

To reauthorize Veeam Data Cloud, do the following:

1. Log in to Veeam Data Cloud for Microsoft 365 with an administrator account.
2. In the main menu, click Settings.
3. In the Settings menu, click System.
4. On the System page, in the Microsoft 365 tab, go to the Reauthorise Veeam Data Cloud section and click Reauthorise.

If you have a multi-tenant app registration, click Reauthorise the customer on the multi tenant app registration.

5. In the Reauthorise page, copy the generated code to connect to your Microsoft tenancy.

6. Click the https://microsoft.com/devicelogin link, paste the code you copied, and click Next.
7. Select the Microsoft account under which you want to authenticate against Microsoft 365. The account must have the Microsoft 365 Global Admin permissions.
8. Click Continue and close the window.
9. In Veeam Data Cloud, click Reauthorise existing app registration.