I tried to add new texture and paint on the terrain, but the texture turns in pure black ?

Help!
I follow same ways as before to add new texture picture to Unity and paint it, however, it turns out painting in black only! I painted many times before and never happen like this. Do anybody know why this happen? ? Please help! Thanks

 

Just want to point out the fact that when you irritate people by flooding your thread with entirely unrelated tags, you are less likely to get those same people to help you.

cache server, package manager, crash.... really?

 

This has happened to me when I've added more than 32 textures. I think there is a texture limit ( at least there was in Unity 2018.2).

 

Thanks for your reply! It makes sense!