If you got this in your AX 2012 (when you are compiling / synchronizing or trying to work with temporary tables that have their TableType set to TempDB):
Cannot execute a data definition language command on (). The SQL database has issued an error.
SQL error description: [Microsoft][SQL Server Native Client 10.0][SQL Server]CREATE TABLE permission denied in database 'tempdb'.
or see this in Event Viewer:
Object Server 01: The database reported (session 3 (Admin)): [Microsoft][SQL Server Native Client 10.0][SQL Server]CREATE TABLE permission denied in database 'tempdb'.
you should definitely setup the access rights for the user used for the AOS service. On the SQL Server instance used, in the TempDB system database add the AOS's account as a user and set it up with the db_datareader, db_datawriter and db_dlladmin role membership.