This license key is invalid
License UI shows licenseRequired.statusMessages.invalid_key (This license key is invalid.).
Why this happens
Typo, truncated key, wrong product key, or key that never existed. Distinct from expired/revoked/domain-mismatch status lines and License could not be verified (unknown/connectivity).
Diagnose and fix
1. Copy the key again from your xfileultra.com account (no extra spaces).
2. Activate/replace in Admin → Settings or the install wizard.
3. See License key is required if the field was empty.
4. See What the license key does / Could not activate the license key.