Error message reading Layout file



I’ve been using Layout 2017 for the past week or so, and I’m suddenly getting an error message telling me Layout is unable to read the Layout file, even for multiple backups of the same file. With no further diagnostic information, I’m not sure what to try next. It’s a very large file, referencing multiple Sketchup models. But until recently, I haven’t had any trouble opening or working with it. I’ve copied it to Dropbox:

Any ideas of things to try?