Be careful of reserved names for site codes
Suppose you've created a new site named 'CON' and are having trouble with it. The reason for this is that you've used a Windows reserved name for your SMS site code. The list of reserved name is fairly short and includes:
The reason that these site codes are reserved is pretty simple. In some places, SMS creates folders using the site code. Since these names are reserved names in Windows and are used for other specific tasks, SMS can't create the site folder.