The message »invalid input» is displayed if the last transaction could not be saved correctly in the database.

How to solve:

1. Identify the receipt-number (transaction-ID) of the last transaction. F.ex. by using the log-screen (top right of main screen) or bay having a look into the reports-section, module »Sales»
2. Tap long onto the »Refund»-Button on main screen.
3. You will be asked for the transaction-ID of the transaction to delete. Enter here the previously identified receipt-number.
4. After confirming, this transaction will be deleted and everything should work again.
5. Do not forget re-registering the transaction you deleted in step 3/4

There is one exception, where the above steps do not solve the problem: If this happens right after a close-day (you maybe will notice it only next morning!), then the procedure above will not help. Please contact us immediately using our CONTACT-FORM if this happens to you. Do NOT delete the application and do NOT try reinstalling it unless we tell you! You could loose all your data and settings!