When calculating payroll, processing errors appear for employees that normally get paid by Direct Deposit: 'No valid EFT bank exists'. (even though an EFT bank does exist)
For employees that have never been paid by direct deposit before:
Go to Payroll / Payroll Employees / Employees. Select the employee and go to the EFT tab. Delete the bank information in the detail grid. Re-enter the banking information and ensure that the Prenote Status field is set to 'approved'. Save.
For employees that have already been paid by direct deposit:
Go to Payroll / Payroll Employees / Employees. Select the employee and go to the EFT tab. The bank information on the detail grid will not be able to be deleted, because it references check details. Put an 'End date' on the line(s) and then insert a new line and re-enter the banking information. Make sure that the 'Start date' is one day after the 'End date' of the original line. Set the 'Prenote Status' field to 'approved'. Save.
After these steps the payroll can be re-calculated and the error should no longer appear.