As the title says. I have just made a texture for my wall in my game, and there is a red line under it. I tried importing it as a PNG and PSD file.
I also tried applying the texture onto a material, but it did not have an affect.
The red line isnt an error 
Its just the color coding for texture assets…
Static meshes are cyan, blueprints are blue, materials are green.
And textures happen to be red…
How does your material graph looks like ?