[Question] What data is stored inside the SessionData folders?

[5ynt4x_3rr0r_]

So I was drawing some gigantic pixel art when my computer crashed. For some reason PDN doesn't autosave your work (at least not by default and on my older version) but I thought my pictures must have at least been cached. I assume that the files it does that in are  C:\Users\username\Appdata\Local\paint.net\SessionData\<someLongNumber>\<someOtherLongNumber>.ch.lz4. My question is, what data is stored inside those .ch.lz4 files, and what can I do with that. Even if I can't use it to recover the work I spent so long on, I'm still very curious about what those files are. I've already tried opening them as a standard picture file (open with > paint.net) and compressed file (open with > winrar) and that didn't work.

[5ynt4x_3rr0r_]

Hmm...

˜  A      ÿÿÿÿ   ðC   KPaintDotNet, Version=4.210.7348.40816, Culture=neutral, PublicKeyToken=nullZ OQ ú.HistoryMementos.Selection + @DataT u#<Saved&   ø>k__BackingFieldy 	+  è   ¸	      P, OCoreû -,V ?BasV .± Ø  t ðbaseGeometrycontinuac 7(<C ¼CombineModeBü$<CumulativeTransform% Ÿ!<Interim"  "a¤Rendering.” @Listˆ'  N ÛË  Þ%% s ð Matrix3x2Double4*  X ÿ 	   	   øÿÿÿŒ  ± value__ B  ê _÷ÿÿÿy  p ó	m11m12m21m22offsetX YÀ1    Ó  "ð?   Pöÿÿÿ“ + !   ž · ø ðfrozendeferred  à         	   €        

0   !   D ªUÿ "UU          PÿUUUÿ

history saving maybe?

(those were 2 different files in the sessiondata folder)

EDIT: started up paint.net, new folder + session.lock file inside of it. hmm...

EDIT 2: and it's empty...

Edited October 6, 2020 by 5ynt4x_3rr0r_

[Rick Brewster]

Those files store the data for the undo/redo history items. There's not anything you can do with them. They're LZ4 compressed and chunked up in a way that isn't usable by other software.

 

session.lock file is a marker file that survives for the duration of the process. It's a locked file marked as "delete on close" (or process termination). It prevents the folder's contents from being deleted by another instance of Paint.NET. You can't open multiple instances of the app, but this at least establishes a protocol for ensuring that can't happen.