from the FAQ :
2) The content of the file "scenery.cfg" does not agree with the current installation on the computer, or the content is corrupted and contains wrong path names.
Sometimes the content of the scenery.cfg file is corrupted and certain path names are not valid. This might come from errors while trying to install a scenery, or while manipulating the content of the scenery.cfg using so called scenery-config-editors, or - last but not least - from manual editing the file using notepad.exe or any other text editor.
If path names are not valid, or paths do not exist, then the DataProvider can also not properly create the EFB database.
see also this post :