When Multi Commander starts it will check to see if a new version is available. If a new version is found, you will be asked if you want to upgrade. If you select that option then the update tool is started. You can also do a manual check by either: selecting Menu > Help > Check for Updates or by launching the update tool via Menu > Help > Launch MultiUpdate.
The Update tools can also be started manually by running MultiUpdate.exe, located in the installation folder of Multi Commander.
The Update tool will download the correct update package and then replace all necessary files. The tool works for both the installed and portable versions.
When doing an upgrade be sure to close any running instances of Multi Commander before running the tool. The Update tool cannot replace files that are in use.
If you have configured Multi Commander to exit to the system tray as an icon, then Multi Commander is not actually closed if you just press the 'X' button. To fully close the program, right click on the tray icon and select Close Multi Commander.
The update tool can (optionally) also download beta versions and has some advanced options that can be set if you have issues with it.
Check the document page for MultiUpdate for more information about this tool.
Upgrade Using Installer
You can also upgrade using the installer package. If the installer detects that you already have Multi Commander installed you will be given two options:
Upgrade installation or Uninstall installation.
If you select Upgrade it will replace all necessary existing files with the new, updated versions.