Comment 1 for bug 932867

Can you verify your db type and the version of nova that you are using?

This migration is supposed to remove that key:

nova/db/sqlalchemy/migrate_repo/versions/076_remove_unique_constraints.py

in my testing that constraint was called 'name' but it looks like for you it is called 'instance_types_name_key'

we might need to update migration 76 further.