Invalid or unknown file format?

Question

When I tried to access contents of an ISO I downloaded, I got the message "Invalid or unknown file format". What does it mean and how to access my files?

Answer 1

This message indicates that UltraISO is unable to open selected image because it's not compatible or the image has been corrupted to a level that's practically impossible to access the contents. At this point you will have to obtain the image file again and then try to open it in UltraISO one more time. UltraISO has a recovery feature called Super Restore, but if that's not working properly, then you still have to obtain the image file again.