At 19:49 of the first period in the Bruins/Senators game, Ottawa requested a Coach's Challenge to review whether a Boston player interfered with Ottawa goaltender Craig Anderson prior to David Pastrnak's goal.
After reviewing all available replays and consulting with NHL Hockey Operations staff, the Referee confirmed no goaltender interference infractions occurred before the puck crossed the goal line.

Therefore the original call stands - good goal Boston Bruins.
Since the Coach's Challenge did not result in the original call being overturned,the Ottawa Senators forfeit their time-out.