The Umbraco Installation Wizard can manage patch upgrades (e.g., 4.5.1 to 4.5.2) and single major version upgrades (e.g., 4.0 to 4.5) gracefully and is the recommended approach for upgrading an installation. With all upgrades, knowing whether your installation contains any modified source or files from the original distribution is important. If so, take care to make backup copies of these files. In addition, if your installation contains a customized web.config file, or other configuration file, creating a backup of your configuration files for later use is essential.
Typically, a patch upgrade contains no new functionality and requires no changes to configuration files. Reading the notes associated with a new Umbraco release prior to installing or upgrading an installation is good practice because any changes to configuration files will be documented in the notes.
The process to complete a patch upgrade is generally as follows:
You can always find the latest release of Umbraco at the Umbraco home on CodePlex at http://umbraco.codeplex.com/releases.
Unless specified in the release notes, you will only copy the following directories to your installation:
After the files are copied, open a browser and navigate to your Umbraco instance. ...