'Quota Exceeded' error
Summary
When storage quota is exceeded, new backups will fail until you have ordered more storage and increased console the quota limit or removed backups (Please note that usage will be recalculated each day, so removal of a backup will not immediately represent the new usage
Screenshot taken from the Acronis portal
Solution
Order the required amount of storage
Set the new quota for the backup user:
Click 'Backup' in the left-hand menu and click 'Actions' > 'Change Settings' and specify the new quota or check the checkbox
Should all usage be correct and the quota has not actually been exceeded you can also check The cloud storage quota is exceeded for 'backup@domain.tld' Further backups will fail for another possible solution