Facebook friends avatars

I get links to Facebook avatars of friends. I load this using game.load.image ()
Then I check if the image is in the cache. And if so, then I show the image on the screen.
This works in 99% of cases. But sometimes an error appears:

Failed to execute ‘drawImage’ on ‘CanvasRenderingContext2D’

What could be the reason?
Links to friend avatars always look the same.