Copyright © 2016 MariaDB. All rights reserved.
Get the Free Gartner Report on Optimizing with Open Source
Maybe there is an error in the documentation?
TRADITIONAL is equivalent to: STRICT_TRANS_TABLES, STRICT_ALL_TABLES, NO_ZERO_IN_DATE, NO_ZERO_DATE, ERROR_FOR_DIVISION_BY_ZERO, TRADITIONAL, NO_AUTO_CREATE_USER
When setting sql_mode to TRADITIONAL, it's actually set as specified above, including TRADITIONAL again, so no error.
Download MariaDB and start working immediately! You can also get subscription details and learn more about the advantages of MariaDB's additional service offers.