* line 492 of /lib/dml/moodle_database.php: ddl_change_structure_exception thrown
* line 1070 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
* line 77 of /lib/ddl/database_manager.php: call to mysqli_native_moodle_database->change_database_structure()
* line 425 of /lib/ddl/database_manager.php: call to database_manager->execute_sql_arr()
* line 370 of /lib/ddl/database_manager.php: call to database_manager->install_from_xmldb_structure()
* line 606 of /lib/upgradelib.php: call to database_manager->install_from_xmldb_file()
* line 1869 of /lib/upgradelib.php: call to upgrade_plugins()
* line 694 of /admin/index.php: call to upgrade_noncore()
