This is in reference to the shapeshifter card from unhinged whose name is all underscores.

http://deckbox.org/games/mtg/cards?f=47c2hhcGVzaGlmdGVy!532
http://deckbox.org/mtg/_____

Clicking on it redirects to http://deckbox.org/games/mtg/cards with the error message "No such card found. Please check your spelling, or use a partial name."

Thanks for the report! Fixed for upcoming release.