HTTP/1.1 507 Insufficient Storage quotaLimitReached - Insufficient Space Available - The given action cannot be completed because the user has reached their quota limit
If you receive this error while backing up files to OneDrive Business cloud storage via SyncBackPro, it may be because you have reached your storage quota. In other words, you've run out of storage space.
In the case your account is a member of a Microsoft Family Plan, there is a possibility that you may receive this error even if your account has still plenty of free space. If this happens then it could be because the owner account of the Microsoft Family Plan has run out available storage space.
In any way, being warned about running out of storage space, wrongly or not, is a warning coming from the cloud storage server itself and not SyncBackPro so you need to address and rectify the problem first before attempting resuming your uploads since SyncBackPro cannot do anything about it.