i use blender 2.77 to make models for unreal and i allways get errors so i used this tutorial
and it works but i still get this massege
Warning test has degenerate tangent bases which will result in incorrect shading. MikkTSpace relies on tangent bases and may result in mesh corruption, consider disabling this option.
when i use smooth option in blender how can i fix that or it dosent matter ?
Oh hey, I put that tutorial up 
It’s pretty outdated at this point, as blender’s exporter has been updated since then.
short answer is: if you are working on something for yourself and the model looks fine I would not worry too much about it. If it is causing problems, double check to be sure the model has been properly UV unwrapped in blender and maybe run it through the ‘remove doubles’ procedure as well for good measure.
thank you
In your import options you could also change Normal Generation Method to “Built In.” This should fix the issue as well. Even after properly unwrapping my mesh, there were still visual errors. Changing that option will help.