To resolve this XBRL error, you will need to reset your ATO credential in HandiTax.
Follow the steps below:
Log in to HandiTax.
Go to the Lodgment menu and click Set ATO Credentials.
Even if these fields are already populated, click the ellipsis to re-select the keystore.xml file, and re-select the credential from the drop-down menu.
Type in the password and click OK.
Restart HandiTax.
Select the tax return and check for Errors.