Customer provided this suggestion:
wcm-post-migration-data-update -DPortalAdminPwd=password -DWasPassword=password -DpreviousPortalVersion=previous_portal_version
Should be -DPreviousPortalVersion= the P is uppercase
wcm-post-migration-data-update -DPortalAdminPwd=password -DWasPassword=password -DpreviousPortalVersion=previous_portal_version
Should be -DPreviousPortalVersion= the P is uppercase