This does not seem to be case. Like what I mean is that the file CAN be opened with ONLY paint.net nothing else can read the file websites,not even file browser. The wierd thing is that this is happening to ALL of my png files even the ones which I never edited with paint.net. all of this changes only happens after the update.
The update was in paint.net itself it told me there was an update and I told it to update it after I exit it.