Have you ever had this problem?
"could not complete your request because an unknown or invalid JPEG marker type is found"
Just happened to me and the answer is hopefully simple to cure. It would seem that a file extension is incorrect. EG. you think you saved it as a .PSD but it has become a .JPG. The file looks ok and you can see it but it won't open. Don't know why it happens but the wrong extension causes a conflict. Simply go into Photoshop or your chosen software and go File > Open, select your image file and choose 'open all readable documents' or if that fails, try opening it, one by one, with your most popular extensions like a .PSD or . TIFF or .NEF or .CAF etc if it is saved as a .JPG or vice versa. IE. file name is "landscape.jpg" try changing the extension to "landscape.psd" or "landscape.tiff" etc etc.
I was born in Blackpool, Lancashire, UK. I am a professional photographer based in London,UK and have been a pro for over 15 years. I am married with a beautiful 8 year old daughter called Sienna.I shoot interior/exterior architectural photography and also shoot stock images of landscapes and travel. I have written three books on digital photography and now do one to one workshops and small groups helping to teach people about this addictive hobby!