A log file is created by default when running an export or import. If an export or import fails for any reason, the log file can be viewed for hints as to what failed, and also can be sent to SourceGear technical support for further diagnosis.
The log file is configured in the same way as other Vault client apps, with the use of a .config file located in the same folder as the executable. In this case, it is the VaultFolderExportImport.exe.config file that controls whether and how to output log information.
The config file allows you to turn logging on or off, specify an alternate location for the log file, and turn on additional logging classes to get more output. See the explanations within the log file for more information.