we first officially introduced SUM up2dates in version 4.2. So for your SUM 4.000-2 you have to do the well-proven backup restore upgrade path i.e. backup your configuration in the SUM WebAdmin, install a new SUM ISO and then restore your backup.
Note: SUM 4.2 doesn't fully support UTMs below 9.2! Read the release notes. Depending on your UTM versions you may want to have SUM 4.1 instead of 4.2.