Restart the application

I mean close the arcgis entirely and start afresh

Try to relocate your dem into C drive and run the process again. If you still face the issue, change the .net framework as suggested by SWAT.

Also, you could change the directory of your model and DEM file.

Intersted.

I do suggest changing the directory of your files into C drive and try again, It should work.

Make sure your DEM is projected, restart the program and change the project directory into drive with enough free space.

There may be errors in DEM, land use data or soil data

Thank you everyone. Problem has been solved.