In HandiTax when changing the lodgment mode to ATO Credential Authentication the Error: 'unhandled exception' may occur.
Open HandiTax directly on the server and change the lodgment mode there.
Go to Lodgment, Set ATO Credentials.
Change the setting from Access ATO Gateway, to ATO Credential Authentication.
Enter your credential password, then click Ok.
Close HandiTax on the server.
Log in to HandiTax on the workstation.
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.
If the above solution still does not work, copy the Machine Credential .XML File (e.g. Keystore-new.xml) file into the <Server>\HSoft folder and then browse for the keystore file. Set the correct lodgment mode using the steps below.
Note: This method should not be used after January 2026. See Switch Gateways for important information regarding this change.