I followed the steps suggested by @kazuhito and it is set to the GRASS folder.
However when I close, I get error message.
GRASS Folder is set
Error message when attempting to Close - have to Cancel instead
This is branched off from Unable To Clean Incorrect Geometries with Grass
I installed `QGIS Standalone Installer Version 2.18 (64 bit) from QGIS Download Website.
Then I went to GRASS GIS Download page to install
GRASS GIS 7.2.1 (current stable)
No matter what I try, every time I run v.clean I get same error:
This algorithm cannot be run :-( GRASS folder is not configured. Please configure it before running GRASS algorithms.
How to fix this?