XnView Software

I just did some more testing here, and if I set the conversion quality to any value other than 100, the conversion goes through successfully. It seems that the problem only occurs in lossless conversion.

Even so, the upload didn't work :/

Of course!
Just remove the jpg extension from the file I added so the site accepts the upload.

They are already installed

I'm using Windows 11 24H2

Any jpg file I try to convert, this happens. The resulting heic file can be opened and viewed in XnView, but any other app on Windows can't open it, like Photos, Paint, Affinity Photos or any other.

When converting some .jpg file to .heic using the program, Windows can no longer open the image. In previous versions this did not happen.