I had an issue with my download of Unity because I didn’t have enough space on my hard drive. I loaded it into an external drive and it seems to run fine except I cannot find the asset folder. So I imported the .blend file from my project folder and that worked but it wont display in the scene.
I get this warning dialog:
! Can’t calculate tangents, because mesh ‘pin_outline’ doesn’t contain normals.
…and the pin won’t display.
Any advice will much appreciated.
Thank you.
What version of unity and blender are you using?
So, here we are a year later after this question was asked… I’m having the exact same problem with unity… I modeled the pin, saved it as a .blend in my project folder for unity and it imports everything but when I drop it in the game I get a plain black outline with the " Can’t calculate tangents, because mesh ‘pin_outline’ doesn’t contain normals." error…
Have you sorted out this issue?
An actual year later! 
Dunno anything about Unity and I’m not about to start now. It’s a project I’m leaving until I’m familiar with Blender in about a year or two, BUT I had the same issue - “Cant calculate tangets… doesnt contain normals”
Before I proceed- don’t forget to apply your Transforms and sort out your Normals before exporting/saving to the Unity Assets folder. This might even resolve the issue without having to resort to the “solution” below.
Since it seemed like an importing issue, I resolved it by exporting the file as a .fbx, then on the right-hand side of Unity in the “Inspector” window/widget, under “Normals & Tangents”, I played around with the settings and it imported correctly once I changed the dropdown item next to “Tangents” to “Import” (same as in “Normals” above it).
*Sadly, this means I won’t be able to do “live editing” between Blender and Unity, I suppose - unless I can permanently change this setting elsewhere.
I dunno how this will affect anything in Unity since before today I haven’t even opened Unity- let alone changed any settings, but for now it resolved the issue.
Anyone familiar with Unity who can maybe weigh in if this is detrimental in any way?
