When i want modify the id column type from bigint to bigserial, there is an error: "Reason: liquibase.exception.DatabaseException: ERROR: type "bigserial" does not exist"

My code:

<changeSet id="change_id_type_to_bigserial" >
    <dropSequence sequenceName="position_data_id_seq"/>
    <modifyDataType columnName="id" newDataType="BIGSERIAL" tableName="position_data"/>
</changeSet>

What is wrong?

// it is so wird for me, because this snippet of an other part of code is working:

<column name="id" type="BIGSERIAL">
            <constraints primaryKey="true"/>
</column> 

//