Today my Dropbox decided it should go haywire and rendered obsolete the Sketch file I was working on. After wrangling with Dropbox restore and Backblaze, I succeeded in getting my file back with minimal loss of work.
Then, I noticed that the file was marked as "Sketch Drawing (Old)." Is there a way to convert these to the new file format introduced in Sketch 3.1?
Having the design as a single file instead of a folder should make it more resilient to similar problems. Googling and going through the menus didn't help.