Azure Storage API changes may effect your Azure Backup Agent on machines.. read more.

The Azure team is removing an older version of the Azure Storage API that’s no longer supported. Because you may be using an older agent, you’ll need to update your Azure Backup agent by October 2, 2015, to help ensure that backups continue operating as expected.

They recently implemented critical updates for Azure Backup to help ensure that backups continue to send to Azure. To help make sure that your Azure Backup agent continues to work as expected, you’ll need to install an update by October 2, 2015.

This update is necessary because the older Azure Backup agents use a version of the Storage API that will be removed soon. This causes backup failures for machines using the older agents. The new agent helps fix this by communicating through newer versions of the Storage APIs.

Additionally, machines registered using older agents will receive the error , “A server registration certificate was not available to authenticate this server with the backup service.” The known fix is to re-register the machine, and the new agent will avoid any operation failures because of this error.
For more information and instructions on how to install the update, please visit the Azure Blog.