-- Using the update functionality of the Synchrony Installer, the Installer stops after having accepted the license.

In the install.log file, the INFO message has been logged:

INFO  SynchronyInstallManager.displayDialogMessage (message=Directory does not exist: Settings\Temp\2\SynchronyInstaller22771\Axway.test.22771\Settings\Temp\2\SynchronyInstaller22771)

A temporary folder is created each time the installer is launched. It is meant to be created under the "Document and Settings" folder.

-- The INFO message is usually related to the TEMP or TMP environment variable in the OS itself, as the installer is using this variable to create the folder.

Consequently, it is necessary to check the TEMP and TMP variables of the machine on which Synchrony is installed.
It is necessary that the Synchrony user has access rights to that folder and that the folder name doesn't contain spaces without double quotes.