Once you had imported SAP DB Version 7.4, you were not able to start the INPLACE migration because no preparations had been made in the original database version for migration.
1. Import the original database version again.
3. Shut down the database instance.
4. Run the Database Manager CLI command migrate in a utility session while the database is in ADMIN mode.
This deletes data that is no longer support in Version 7.4.
5. Import Version 7.4 again and restart the INPLACE migration.