While opening OpenBuildings Designer, you might get an error saying that "TFDIR_SETTING points to an invalid path". Sometimes, this error may be associated with another error regarding "Default.lay" and/or "Default.trs" file(s).
This problem may occur when you are appending the already assigned value of the TFDIR_SETTING with a path to a custom settings folder. OpenBuildings Designer supports only one path for the TFDIR_SETTING variable.
It is recommended to overwrite the already assigned value if you would like to assign a path to a custom settings folder for this variable. This would resolve this issue.