When we upgrade to AX 2012 the destination database needs to be in “upgrade mode” othewise the upgrade checklist it not triggered correctly. This can be done in one of two ways… either you check “Register this database for Upgrade” when you set up the AOS… this implies that you actually set up a new AOS. If you do not want to do that you can also do this:

1. Start SQL Management Studio and run this script:

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE PROCEDURE [dbo].[SETUPVERSIONPROC] AS SELECT ‘6.0.947.0’
GO
DELETE FROM SysSetupLog
WHERE NAME = ‘SysCheckList_Setup’
OR NAME LIKE ‘SysCheckList_Up%’

Links
https://blogs.msdn.microsoft.com/axsupport/2012/11/16/ax2012-upgrades-setting-a-clean-ax2012-database-to-start-with-the-upgrade-check-list-and-not-the-initialization-check-list/