Most time this error is because a PNG file has been named as a JPG file. A quick way to see if this is the case, is to drag the offending file (which has the JPG extension) onto your web browser page. It should open and display your image no matter what. Right click on the image and select "
View Image Info". When that's displayed, click on the "
Media" tab and you should see similar to this ...
The "
Type" is displayed as
PNG Image and does not match the extension of the viewed image, which is
JPG.
To open it in PS, simply rename the extension to match the actual "
Type" which in this case is
PNG.
I hope this helps others that may have the same issue, I know I've had it on a number of occasions and it has worked every time.
Cheers.