Hi there madelaine,
It's important to fix any errors before submitting the return again. With the error code CMN.ATO.GEN.XML01, this rejection error is commonly seen when the return exceeds the maximum number of 10 foreign income worksheets. If this is so, please consolidate the foreign income worksheets, with the 10th entry being the combined amount of the remaining amounts. Group the remaining records by the income type. Also, the error code CMN.ATO.GEN.XML03 means there's an invalid character somewhere in your payroll information in MYOB. Invalid characters are "[]!! # $% *;; = @ <>\ _ { } ^~`". You'll need to check for (and remove) any invalid characters in your employee cards and payroll category names. You can also check out this link.
Best regards,
Doreen