When an export towards Xero fails please check if anything has come across despite the error message. If this is the case, it is strongly advised to delete those transactions in your accounting software before trying to export again. If not duplicate entries will be exported.
The next step would be to check if the connection between both platforms is still active. You can check this via the integrations tab and by clicking on the synchronisation tab.
If the synchronisation between both accounts was successful, the following will appear:
If the synchronisation between both accounts was unsuccessful, the following will appear:
In this case, you will need to fully disconnect and reconnect.
The next step is to check the error message you received. You can find this message by opening up the detail of the export report.
Click on the relevant error message to see how the issue can be resolved: