Using the PredictWind App if the Weather Routing fails to complete it could be due to a number of reasons.

1) Start and finish waypoints are not in clear open ocean.

Please move your start or finish waypoint to deeper water.

2) Depth contours set low for the route.

Please check Depth Contours select say 2 metres if set to 5-30 metres.

3) Comfort settings set to low for the conditions.

Please check Comfort Settings, for example, wave > you are mid ocean and wave is set to 2.5 metres the router will simply fail to find a route if you have 3 metre wave conditions around you.