Hello,
I am having a hard time finding out who else has run into this issue, but when I try to run the migration for the data, I am getting this error:
[2020-08-21 18:59:11][ERROR]: Not mapped id key 23 found for eav_entity_attribute.attribute_set_id
I have never seen this before. I know what it's looking for, but it doesn't make sense. There was never an attribute id of 23. And I even went ahead on the older Magento and added in a test Product Attribute Set which then listed the ID as 23. So you would think now that it's created, it would find it, but I'm still getting the same error.
check for the attribute I’d 23 entry in eav_attribute table Magento 1 database
if this attribute is created from 3rd party extension then remove the extension class from attribute entry