UNIQUE Constraint Failed (Error code: 1809)


Error Message: Unique Constraint Failed

Possible Causes

Starting from version 6.3.3, Backup for Windows contains a feature that allows to avoid these cases and restricts the simlutaneous run of two MS SQL backup plans to the common destination (error code 1809)

This error occurs when two or more backup plans (as well as consistency check) with the same source data and target backup destination are running simultaneously.

Also, this may occur when the same file is selected twice in one backup plan.

For operational reasons, MSP360 (CloudBerry) Backup for Windows uses a repository which appears as an SQLite database. This database contains information about files located in the backup destinations as well as the history of operations performed with these files. To learn more about the repository, refer to the Repository Explained article.

A UNIQUE constraint ensures that all values in a column or group of columns are distinct from one another or unique.

To learn more about the UNIQUE constraint, refer to the SQLite UNIQUE Constraint article


  1. Edit the schedule of backup plans that cause the error. Read more about schedule settings for different backup plan types in appropriate chapters of the help documentation:
  1. Run the consistency check.

To learn more about consistency check, refer to the Performing a Consistency Check chapter of the help documentation