igb99

I can now confirm that this problem is not unique to 4.0.19. Just had the same thing happen with 4.0.17. It appears to be caused by Windows Defender re-enabling itself in the presence of another Anitvirus. In my case I run Webroot- so Windows Defender should be off. The latest Windows Update seems to introduced a bug where Defender can get re-enabled. It then seems to cause loads of problems with access errors in the AppData folder. These errors don't just affect Paint.NET. As soon as it is disabled - the errors go away.

I have reverted to 4.0.17 via System Restore, and that is working OK. I begin to suspect a change between 17 and 19 but because I used System Restore there is a chance something else was reverted to earlier at the same time. My Windows 10 1709 has all current updates installed.

I have the same problem - with very similar error messages about access denied to a SessionData folder Recently updated to Windows 10 1709 and latest Paint.net 4.0.19