Sorry, I’m new to ue4 and when i try to drag my foliage the grass is just a grey texture. I’ve been searching forever for an answer but i could find one.
i did the same mistake if you moved a projects content outside of unreal engine it doesnt keep the paths for the textures and materials. so either reapply the textures or move the folder back to the default place to in content folder to correct the textures and materials path.
Thank you for the answers 
i fixed the issue
Hello vbossbla
Did you solved the problem by given answers or in another way? If with answers, can you please mark this thread as “RESOLVED” for other mambers can find the solution in future? If you solved in another way, can you write the way for us, please? Thank you.
Guys please help me I have same error and didn’t find that solution