There are two situations when this error can occur:
1. When a document has been exported as a Purchase Invoice first, then switched to Sales and re-exported again as a Sales Invoice.
2. When a document was previously exported to a Xero organisation and you wanted to re-export it again to a different Xero. For example, when you moved the document between folders connected to different Xero organisations.
Note: When a document with the status ‘ready’ is moved across folders, there should not be such problem.
To resolve this issue, please delete the document and upload it again to Datamolino.