Upgrading is moving to a more recent version of SMF by getting a fresh set of all necessary files. It is necessary when moving from an earlier major version to a more recent one (SMF 1.1.x to SMF 2.0.x, for example). It may be necessary if patching does not work because of customizations or modifications of the code. It is different from Installing SMF or converting to SMF from another forum software. If you want a clean start with the same version you have now, take a look at How to upload a fresh set of files. For more information, see upgrading