There are no special requirements for the upgrade to SAP Web Application Server 6.10 (or higher). The Note Assistant is part of the standard release.
For technical reasons, the Note Assistant is not available during an upgrade to Releases 4.6B, 4.6C, or 4.6D. You must reinstall it after the upgrade and before the modification adjustment (transaction SPAU) has been performed. The modification adjustment needs the Note Assistant to reimplement note corrections or to reset note corrections to their original version.
The upgrade to 4.6D includes additional preparation and follow-up activities.