Poly cord coming out of awning rail.

The prevention is easy as there should be a screw in each side to hold it in place.

The solution may not be easy. Remove all tension from the canvas using ropes or whatever works. They try to push the cord back in but that may not be possible. In that case remove the roller and canvas from the rig and then work the cord back in place and then reinstall the roller and canvas.

The poly cord keeps the fabric from pulling out of the groove in the awning rail (as well as the roller bar for the other end of the awning). As long as there is tension on the fabric, there is no chance of pushing the poly cord back into the fabric loop around the poly cord. Try extending the awning a foot or so, then push the roller bar back toward the awning rail to relive the tension, then try to push the poly cord back in. No guarantees, but it should work.

There should have been a screw through the awning rail on each end of the fabric to keep the fabric and poly cord in place so the awning rolls up straight.