I am trying to migrate a shop from Shopware 5.4 to 6.6. Products, Categories and Customers are no problem, but the orders won’t work at all.
The log of the migration run is filled with these logs:

[error] SWAG_MIGRATION_RUN_EXCEPTION
An exception occurred
Entity: order_document, sourceId: 019039ce2d3b7057a9f6ad4ca697470d
An exception occurred while executing a query: SQLSTATE[23000]: Integrity constraint 
violation: 1452 Cannot add or update a child row: a foreign key constraint fails 
(`c1w2db1`.`document`, CONSTRAINT `fk.document.order_id` FOREIGN KEY (`order_id`, 
`order_version_id`) REFERENCES `order` (`id`, `version_id`) ON UPDATE CASCADE)

I assume that these errors mean that the related order was not created correctly. But I only get around 50 order related errors in the migration log and almost 4000 of these document related errors.
There are more than 3500 orders in total to migrate and currently none gets migrated.