Consistency Check Warnings (codes 2503, 2504, 2505)


A backup plan terminates with one of the following warnings:

  • Consistency Check detected an issue. An excess restore point was found and marked as forbidden. A full backup was forced

  • Consistency Check detected an issue. Latest restore point is marked as 'forbidden' and will not be used. A full backup was forced

  • Consistency Check detected an issue. Generation number collision due to simultaneous backups from cloned instances


All these warnings (codes 2503, 2504, and 2505) have a common cause. In some cases, two or more backup plans with the cloned instances in their backup source can run simultaneously and back up different copies of the same content. This leads to a situation when backup plan settings, deduplication database, and current generation on backup storage are identical.

This may invoke restore point conflicts because similar restore points are created for different machines. Thus, one of the restore points is marked as 'forbidden', and a full backup is forced to start a new generation on backup storage. Once a 'forbidden' restore point is detected, this also forces a full backup for the other cloned machine (warning 2503, 2504).

Since it is not possible to determine unambiguously which instance created the generation on backup storage, generations must be separated.

To learn more about the generations, restore points, and new backup format in general, refer to the New Backup format section of the help documentation


For Standalone Version

The easiest solution for these warnings is a backup plan cloning.

To Clone a Backup Plan

  1. Switch to the Backup Plans tab.
  2. Find the plan that produced this warning on consistency check.
  3. In the bottom menu, click Clone Plan.

  1. In the Clone Plan dialog box, specify a new name for the cloned backup plan for easier distinction.

  1. Run both backup plans.

Clone Backup Plan Using CLI

using CLI applies for Hyper-V backups only

To clone a backup plan using CLI, run the following command:

cbb addHyperVPlan -cloneplan {newname}

where {newname} is the name for the cloned backup plan.

For Backup Agent in Managed Backup

The optimal solution for these warnings may be the backup prefix change.

To change a prefix, proceed as follows:

  1. Run Backup Agent.
  2. In the application menu, select Edit Storage Accounts, then select the required storage account.
  3. Click Advanced options.
  4. In the Backup Prefix field, specify a new prefix, then click OK.

  1. Run the backup plan again.

To learn more about backup prefixes in Managed Backup, refer to the following chapters: