OneDrive for Business backup may fail with error "The provided client secret keys are expired"

OneDrive for Business backups are failing because the client secret (application secret) is expired.

Symptoms

OneDrive for Business backups are failing with the following error:

(ERROR_ERRORS_ENCOUNTERED))-Exception: System.AggregateException: One or more errors occurred. ---> Microsoft.IdentityModel.Clients.ActiveDirectory.AdalServiceException: <AAD_ID>: The provided client secret keys are expired. Visit the Azure Portal to create new keys for your app, or consider using certificate credentials for added security: https://docs.microsoft.com/azure/active-directory/develop/active-directory-certificate-credentials

Causes

The Azure client secret (application secret) used to configure the app is expired.

Resolution

1. In the Azure portal, create a new secret for the Azure application. After the secret is created, copy the value, and then update the application secret in the Metallic console. For information about creating a secret in the Azure portal, see Create a new application secret on the Microsoft website.
2. In the Metallic console, manually run a backup operation.