Description
The Input Cost Surface parameter value contains cells with zero values or negative values.
The value at each cell location on the cost raster represents the cost per unit distance for moving through the cell. Each cell location value is multiplied by the cell resolution while also compensating for diagonal movement to obtain the total cost of passing through the cell. The Zero Cost Handled As parameter converts zero and negative values into either NoData (barrier to movement) or a small positive (low cost to movement).
Solution
This is warning message. If this warning is unexpected, see Adjust the encountered distance using a cost surface.