Error opening bone animation

I just made rigging with bone layers, and everything goes right. But when I try to re-open the file, the error message pops up and I cannot open the file.

The error message says
Unable to load “filename”:
file.sifz:<bone_valuenode>13932: error: Unexpected element <bone_valuenode>
file.sifz:<bone_valuenode>13932: error: bad data in <bone_valuenode>
file.sifz:<bone_valuenode>13932: error: parse of “parent” failed <bone_valuenode>

The possible problems are:

  • I made an error and crashed synfig while doing bone animation before(of course I deleted that file now). That maybe made something wrong.

  • I imported bone animation. Then I exported the canvas.

Edit: I did some experiments, and found the problem was that I exported my canvas. The problem is I can’t recover the file…