Add this entry to ignore file in migration config principal
.
and run again, it will work.
All these table names and fields which are not "standard" need to be either ignored or mapped in your version of the map.xml.dist
configuration files.
add this line:
<source>
<field_rules>
<ignore>
<field>store_group.code</field>
</ignore>
<ignore>
<field>store_group.group_id</field>
</ignore>
<ignore>
<field>store_group.website_id</field>
</ignore>
<ignore>
<field>store_group.name_id</field>
</ignore>
<ignore>
<field>store_group.root_category_id</field>
</ignore>
<ignore>
<field>store_group.default_store_id</field>
</ignore>
Or you can add tables to ignore like this:
<ignore>
<document>core_config_data</document>
</ignore>
<ignore>
<document>store_group</document>
</ignore>
<ignore>
<document>store</document>
</ignore>
<ignore>
<document>store_website</document>
</ignore>
for more info go to Magento 2 documentation.
https://devdocs.magento.com/guides/v2.3/migration/migration-tool-configure.html