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 session logs: The identity of the calling application could not be established.

To reauthorize Veeam Data Cloud, do the following:

1. On the Microsoft 365 page, click Manage next to the tenant you want to work with.
2. Select Settings.
3. Select the Microsoft 365 tab.
4. In the Add a Second App Registration section, click Reauthorize.

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

5. In the Reauthorize window, 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 for Microsoft 365, select one of the following options:

• Click Reauthorize existing app registration to reauthorize and continue using your existing application registration.
• Click Create new app registration, to create a new application registration.