"This save relies on content that is no longer present. Some objects may no longer be available. Continue loading?"

After I installed the latest update, I get this message when I try to load a save. It is my understanding that this usually means that there is something up with DLC, but I checked all mine and it's fine. I really want to play because of the new update, but I'm scared that if I save and something is really missing, I might save over it and lose it forever... Any advice as to what I should do?

Thanks in advance.

Validate your files

What do you mean?