You can’t open a backup. They must restore it first. Then when they open it, it will upgrade to the 2018 version.
Resolution for 'Accountant 2017 issue: 'Backing up from Desktop Accountant 2017 to restore to Enterprise 2018' available: Yes.
The Accountant 2017 issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the Accountant 2017 issue yourself by looking for a resolution described in the article. If it is a complex Accountant 2017 issue or you are unable to solve the issue, you may contact us by clicking here or by using other Accountant 2017 support options.
For more information about resolving issues related to Accountant 2017 in Quickbooks/QBO or to get support for the issue 'Backing up from Desktop Accountant 2017 to restore to Enterprise 2018', click the link below: