Everything on the canvas vanishes and the Iluustrator doesn't allow to save the file.

While working, everything on the canvas disappears suddenly, and the illustrator doesn't allow you to save that file, saying there is an 'Unknown Error'. And yes, NO RECOVERY SETTING WORKS HERE. If the work you have done is not saved till the collapse, then it's simply gone. Even if you copy all elements of that file to a new file, you won't be able to save that file either.
This issue was there with the previous version (29.6.1).
That means there is no progress on this BUG. It's still there in the new version