Hi, i'm having the same error. I use save as an when select the folder i want it says than there is no file named x.pdn.
I have seen that this bug appears only en some folders, such as personal folder as My Images, and when there ara many subfolder levels in a secondary HD.
But, i have tried save at my d:\Download folder and it runs. So then i have to move the files.
Hope you could resolve it
I'm using windwos 11 and paint .net 5
Regards