@Retired_mod This does not help resolve the issue. I am experiencing the same issue when following the above pointers. Here is the statement:

response = w.statement_execution.execute_statement(
    statement='ALTER TABLE users ALTER COLUMN :col_name SET NOT NULL', 
    warehouse_id='<warehouseID>',
    parameters=[{'name': 'col_name', 'value': 'user', 'type': 'STRING'}]
)

This results in the same AttributeError outlined by @Phuonganh above.