您需要使用 比较 验证器而不是唯一的.

You need to use compare validator instead of unique.

['new_password', 'compare', 'compareAttribute' => 'old_password', 'operator' => '!='],

因为唯一验证器验证属性值在整个表中是唯一的

Because unique validator validates that the attribute value is unique across the table