ofn-preset-guides

[Ofnuts]

Can you try this in the Python console (Filters ➤ Python-fu ➤ Console)

Copy/paste all of this to the pyhon console (the leading spaces in the last line are important), and then strike enter until the prompt returns to ➤>

Code:

import os.path
fname=os.path.join(gimp.directory,'testfile.dat')
print fname
with open(fname,'w') as dat:
    dat.write('Test successful')

If you get error messages, copy them here. If you don't check that the file whose name has been printed has been indeed created and contains Test successful.