Currently migrations from 6.0 to 6.5 are available.
The steps to migrate your vtiger CRM 6.x to coreBOS are:
execute the script
In some of the migrations we have done, we have found that the version is not correctly updated in the database. Although the code is on version 6.1 the database is incorrectly set to 6.0 (no idea how that can work!!). If this is your case you need to force the migration to apply the 6.1 changes bt adding the force parameter like this: