Assume that you have a database backup that contains a sequence object that is created by using the cache option in Microsoft SQL Server 2012. Then, you try to restore a database from the backup. In this situation, you may receive the following error message:
SQL Error 2627:
Violation of UNIQUE KEY constraint '%.*ls'. Cannot insert duplicate key in object '%.*ls'.
This issue occurs because the cached sequence is flushed incorrectly when you perform the database backup. This makes the value of the cached sequence larger than the value on the disk. In this situation, error 2627 is triggered.
Cumulative update information
Cumulative Update 4 for SQL Server 2012 Service Pack 1
The fix for this issue was first released in Cumulative Update 4. For more information about how to obtain this cumulative update package for SQL Server 2012 Service Pack 1, click the following article number to view the article in the Microsoft Knowledge Base:
2833645 Cumulative update package 4 for SQL Server 2012 Service Pack 1Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2012 Service Pack 1 fix release. We recommend that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
2772858 The SQL Server 2012 builds that were released after SQL Server 2012 Service Pack 1 was released
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.