In HandiTax when changing the lodgment mode to ATO Credential Authentication the Error: 'unhandled exception' may occur.
To resolve the error you must open HandiTax directly on the server and change the lodgment mode there.
Afterwards when changing the lodgment mode on the workstation, the error will no longer occur.
If the above solution still doesn't work, please copy the Machine Credential .XML File (eg. Keystore-new.xml) file onto the <Server>\HSoft folder and then browse for the keystore file. Set the correct lodgment mode using steps below.
Steps to change the lodgment mode:
Open HandiTax in the year with the issue
Go to Lodgment, Set ATO Credentials
Change the setting from Access ATO Gateway, to ATO Credential Authentication
Enter your credential password, then click Ok.
Restart HandiTax
Attempt your lodgment or prefill again.