Do you mean 6.5.16? There is not a version 16 of Sugar.
If you are using Community Edition, Sugar 6.5.x is the last version of that product that was ever made. They might be a patch that is newer, but SugarCRM stopped distributing Community Edition some time ago, so finding an upgrader to a 6.5.x patch can be challenging.
If you are using a licensed version of Sugar (Professional or Enterprise), Sugar 9.x is so radically different from Sugar 6 and most of the versions between 6 and 9 have been out of support for so long that my recommendation would be to migrate your data and customizations from your current Sugar app to a new install of Sugar 9, and/or contract a partner to assist you.
