Error:
Solution: According to ATO troubleshooting article https://www.ato.gov.au/general/online-services/technical-support/troubleshooting-for-businesses-and-tax-practitioners/ please let the user try following:
If the issue will not be resolved, may we please ask the user to contact ATO directly by phone and provide them this error code - this way ATO will respond much faster. If it won't help, please let us know, then we will raise the incident with ATO tech team.