This error indicates that its likely that the ATO site is down:
Contact the ATO and mention the error codes mentioned in the description of the error.
Re try to lodge the Tax return again after few hours.
Tax Manager and Elite Forms: Error: 'CMN.ATO.GEN.EM0001'
'CMN.ATO.GEN.EM0001 An unexpected error has occurred, try again. If problem persists, contact the ATO. Error code 700, 701, 1003'.
Updated over a month ago