There was a problem with a 3dn I was working on. It was causing the emulator to hang when I tried to load it. I could load the backup file, but when I made any changes to it and saved, it would cause a hang next time it was loaded.

Could you post here the 3dn file pls

Here is the broken one

Donkey Kong (U) (PRG1) [!].3dn

And here is the backup

Donkey Kong (U) (PRG1) [!].bak

I will look at it immediately

Let me know if you have any luck. I have another one doing it as well.

https://www.dropbox.com/s/dr4e128y6y0xlw8/Fix1.zip?dl=0

While i can identify the freeze bug and fix it (try the quick-fix 3Dnes version above). I can not reproduce the corrupt 3dn file from the back-up one.

Could you pls try the new version with the back-up 3dn? If it still produces a corrupt 3dn with your new adjustment, pls report the exact steps to reproduce it.

It no longer causes it to hang, but it does give the following error - "An item with the same key has already been added." - and all the 3dshapes revert back to their default settings losing all of the edits that were made.

The steps taken were:

Open 3DNes.

Load the rom.

Click on the item to edit. In this case, I chose a rolling barrel that had SizeZ set to a different value than the rest of the frames. It is set to 12 while the rest are 10.

I adjusted the SizeZ value from 12 to 10.

Saved the 3dn.

Exit 3DNes.

Reopen 3DNes.

Load the rom.

That's when the error occurs.

https://www.dropbox.com/s/jscxn91v417ivtk/Fix2.zip?dl=0

This ghost bug is gone once and forever. Thank you for the bug report. You can grab the  quick fix above to prevent the bug.

V2.0.1 will be released soon!  

Works great! You are amazing! You even fixed a little graphical bug I chalked up to emulation, where one frame of the little fireball enemy in Donkey Kong was missing the bottom half of the sprite, but only when moving right.  You can see it in the video I posted in the repository. Thanks.