This appears when someone is signed in to Facebook in the same browser as Sphere and causes a communication error between Facebook and Sphere.  The communication error comes from Facebook requesting the URL from Sphere and extra characters may be added. To fix this error you will need to use the Facebook debugging tools.  To access these tools you would click the link that has the "Warning Message" in it.  This will bring up either a new page or tab for a Facebook login.  Once you have logged into Facebook you can then use the debugging tools.  To fix this error you would click the Fetch New Scrape Information.  This will request a new URL from Sphere and correct any issues within the URL.