mariadb ADD COLUMN virtual = You have an error in your SQL syntax

Pls, check create sql query?

ps. screenshot is in attach

So when you change the default value from NULL to let's say "No default", you get no error?

yes and when i create and change field from heidiSql

1. HeidiSql is generate folow sql with error ALTER TABLE good ADD COLUMN attr_prop_int INT DEFAULT NULL AS (json_value(attr,'$.prop_int')) VIRTUAL AFTER attr;

2. I remove the expression "DEFAULT NULL" from sql and the query works well ALTER TABLE good ADD COLUMN attr_prop_int INT AS (json_value(attr,'$.prop_int')) VIRTUAL AFTER attr;