Blender to unity import problem

I’m using Blender 2.63 and everything was fine until I tried to change an animation by deleting a few keyframes then exporting as an FBX back out into Unity. Now I’m getting an error stating, “Can’t import tangents and binormals, because mesh ‘Player_Mesh’ doesn’t have it.” I have been searching for an answer to this problem for over an hour but I’m just not finding it. I don’t have a clue what happened.

It’s 2017 and there’s still no answer to this question and there’s still no explanation of what the error means. I, too, am using Blender and the mesh has unwrapped UVs on it. Sometimes it exports just fine, sometimes it doesn’t.

@obliviousart Never use Blender. It’s a horrible software that you can’t import files from into Unity. I just either make the models in Unity or take from online.

DarkFang100 You start off by calling Blender a horrible software, then tell us to use Unity for 3D Modelling or just fish online for some 3D models.