Seams come unattached for a variety of of reasons...the good news is that generally this is a straightforward repair.
Stitched seams come unstitched due to abrasion, or fatigue of thread.
When restitching a pack we use nylon thread of equal or better quality than the original stitch. Colour will be matched as closely as possible. The repaired seam will be sealed with a binding tape if necessary and possible.
Stitched seam comes unstitched due to stress placed on the seam...the thread pulls away from the material.
If the stitching is intact but the material on one side has pulled away then it is likely necessary to reinforce or add some extra material before restitching the seams together. Every effort will be made to match the colour of the original fabrics. The repair seam will be seam sealed if necessary.