- Get model store from AX 2012.
- Run code upgrade service on model store in LCS
- Estimate manual Code upgrade effort required
- Do the manual code upgrade required
- Run data upgrade
- Run the full model build on upgraded code and data
- In case on premises restore upgraded DB to SQL Server apply upgraded code package from LCS .
- In case Cloud run the data transfer tool to sync data to cloud , apply code package through LCS .
Follow below link for Detailed Process.