Blueprint load error when restarting the editor

I have created a c++ character class to use for the player of my project. I then set up a blueprint based on this character so that I can edit inputs and meshes. Everything works fine but when when I restart the editor and open the project again the blueprint fails to load. Why am I getting this error and how can I prevent this from happening in the future? Image of error attached.

@GrandmaCity Try running the project from you IDE and see if the errors persist.