When you've restored a main data DB of AX 2012 higher kernel version with installed AOS with lower kernel version, the AOS will not start with an error in Even Viewer. Though it is not recommended on production as Kernel version should match with that belonging to DB, but for development or test machine, there is a manual fix to start AOS.
The Event Log shows:
Object Server 03: Fatal SQL condition during login. Error message: "The internal time zone version number stored in the database is higher than the version supported by the kernel (11/8). Use a newer Microsoft Dynamics AX kernel."
To check the restored DB kernel version, run a SQL query on main db as:
USE [Main DB Name]
SELECT * FROM SQLSYSTEMVARIABLES where parm ='SYSTIMEZONESVERSION';
Result show as:
PARM VALUE IPARM IVALUE
SYSTIMEZONESVERSION 11 14 NULL
Execute the query as below to update for matching kernel version to 8 (belonging to installed AOS)
UPDATE SQLSYSTEMVARIABLES set value=8 where parm='SYSTIMEZONESVERSION';
Then, the SELECT query should return:
PARM VALUE IPARM IVALUE
SYSTIMEZONESVERSION 8 14 NULL
Now AOS should start without any issues.
Ideally AOS should be upgraded to match with DB stored version, and above resolution is just a work around to be applied on non-production environment for test purposes only.