000109 : The buffer distance cannot be negative for lines and points
Negative distances can be used when buffering polygon features to create buffers on the inside of the polygon features. Line and point features do not have areas, and negative distances cannot be used with these feature types.
Confirm the feature class used is a polygon feature class and the distance specified is the intended distance. If buffering lines, consider the Line Side parameter for more options in creating buffers. Learn more about Buffer.