An exception occurred whilst trying to authenticate you. Invalid username or password.
This error means Dext can no longer authenticate with your KashFlow account. You need to reconnect the two accounts to resolve it.
Go to Business settings > Connections.
Select Manage next to KashFlow, then select Reconnect.
Follow the steps from the How to connect Dext to KashFlow article from the In KashFlow section onward.
Invalid receipt number
This error occurs when an item has already been published to KashFlow and then deleted there. Dext tags items after publishing to prevent duplicates - clearing that tag allows the item to be republished.
To resolve this, follow the steps in How to republish an item.