Anyone know how to get stuck backing from a rug up

In our guest bathroom, I went to pick up the rug in front of the toilet, for some reason it had stuck so bad to the floor, that when I picked it up, it left all the rubber stuck to the floor. Not just a light coating of it, it's an ugly textured mess. Any one have ideas on how to remove this without hurting the floor. I have attached a photo of the mess.
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