Test upgrade for onsite 8.5 -> 11

Hi everybody, trying to do a test upgrade of a customer from 8.5 - it is at least 3 license model changes ago, so i decided to do a test upgrade via v10 first, but when i try to run CrmSetup.exe to get the db the last way to latest 11, i get this error

PS D:\SuperOffice\Install\SuperOfficeCrmSetup_11.13_HF1\CRMSetup> .\CrmSetup.exe upgrade-existing --database-server “<redacted>" --database-name "SuperOffice" --db-user "crm7" --db-password "crm7myd" --table-prefix "crm7" --so-arc "D:\SO_ARC" --email-client "Outlook2007" --company-name “<redacted>" --serial-number "<redacted>" --license-url "https://license.superoffice.com/LicenseSvc/LicenseService.svc" --system-user "ejSysUser" --system-password "<redacted>" --language "DA" --country "DK"
2026-06-22 15:53:27 [Info] Found a SuperOfficeCdd database
2026-06-22 15:53:27 [Info] Validating license for <redacted> with serial number <redacted>
2026-06-22 15:53:28 [Error] Error during upgrade existing installation
InvalidOperationException: Failed to get license (<redacted>/<redacted>) from server http://license.superoffice.com/LicenseSvc/LicenseService.svc
Upgrade failed!
CDD errors logged to D:\SO_ARC\Logs\Cdd20260622.log

So license wise, what is the procedure for upgrading (or at least making a test upgrade) of such a customer?

Thanks in advance