I started adding groups to one of my libraries and it allowed me to add two, then wouldn't let me add anymore.
I went to site settings, permissions, add group, and created the SharePoint group "Managers toolbox Visitors 3 because SharePoint REALLY sucks".
I go in to add the group from all of the groups I've created:
But, I'm getting this error everytime I attempt to add a group to my library permissions.
Why did it allow me to add two libraries, and create a bunch more but not add any more?