The backpack is a toddler sized pattern, although she does tell you how to upsize it.
I changed the way the straps were made because I wanted the straps to be wider than 1", thinking that wider might be more comfy. But then I had to attach the 2" strap to a 1" strap to fit it through the strap adjuster, so I sewed a piece of 1" nylon webbing into the end of the 2" strap.
From the look of the picture that I got of the failure it looks almost like the nylon webbing just shredded, which caused it to come apart at that point. It may be the material I used, but I am thinking that if I zig zag stitch it across the strap and on a diagonal a few times that may hold it. If not I may have to find a more durable strap material. She is sending them back to me and I should have them on Monday, so I will be able to report back. And I will be pulling hard on those straps and doing a better quality inspection this time!
Someone else asked again, so here is the
BACKPACK PATTERN:
http://www.made-by-rae.com/2009/03/finally-here-toddler-backpack-pattern.html