Error: assets could not be loaded.

{"/assets/no-optimization/spine/popup/Popup.png":"Couldn't load image /assets/no-optimization/spine/popup/Popup.png","/assets/no-optimization/spine/popup/Popup.atlas":"Couldn't load texture atlas page /assets/no-optimization/spine/popup/Popup.png} of atlas /assets/no-optimization/spine/popup/Popup.atlas"}