arcmap error for river slope calculation

[tshewangdorji]

hi frens,
im using aster data of projected coordinate, arcgis 10, hec hms 35, hec geohms 10 it could fill sink, flow driection and all but
   the error occurred when calculating river slope. please can anyone suggest help for this error.

[Eng_A_SH]

This post is from 2013 and I'm here in 2021 facing the same problem with no solution in sight.