Solving Errors With Backup                                 

1.) I always recommend doing a "Download Backup Now" first to make sure you can download, then you can set up the automatic backup.

2.) If you are unable to download the backup, try excluding folders as seen in the image attached here that could be making the backup fail and trying downloading again.

3.) Repeat the process until you can have a successful backup. It could be a conflict with the many plugins or themes available, a timeout issue, or a server conflict. If you continue to have an issue, please contact us directly.

Also, please check with your hosting provider as many times, hosts have issues on their end with certain functions in our product.

Please check WP Backup Plus list of Hosting Service Providers and known Issues