When installing the Azure Backup-agent via the Register Server Wizard you need to supply your vault credentials. If doing so incorrectly you will get the following error:
Microsoft Azure Backup envountered an internal error. (ID: 130001) Wait for a few minutes and then try the opration again. If the issue persists, please contact Microsoft Support.
If the vault-file is located on a network share the wizard will fail.
So a pretty simple fix, move the vault-file to a local storage and try again.