Demo Data Import Failed

I’ve got the following states when importing the demo data:

Failed to import Media “faq-choosing-your-holiday”
Failed to import Media “faq-prep-work-for-travel”
Failed to import Media “faq-medical-requirement”
Failed to import Media “faq-visa-requirement”
Failed to import Media “faq-travel-insurance”
Failed to import Media “faq-travel-day”
Failed to import Media “faq-flight-airport-reminders”
Failed to import Media “faq-self-drive-reminders”
Failed to import Media “faq-on-holidays”
Failed to import Media “beautiful-places”
Failed to import Media “diverse-destinations”
Failed to import Media “passionate-travel”
Failed to import Media “value-money”
Failed to import Media “icon-1”
Failed to import Media “icon-2”
Failed to import Media “icon-3”
Failed to import Media “brazil-destination”
Failed to import Media “ottawa-canada”
Failed to import Media “cuba-old-havana”
Failed to import Media “STS-129 Shuttle Atlantis On Pad 39a”
Failed to import Media “san_agustin_church_manila”
Failed to import Media “austrian-mountain”
Failed to import Media “san-francisco-golden”
Failed to import Media “beautiful-ha-long-3”
Failed to import Media “christian-joudrey”
Failed to import Media “ferry-building-port”
Failed to import Media “blonde-girl-walking-alone-on-3”
Failed to import Media “building-on-port”
Failed to import Media “cable-car-on-3”
Failed to import Media “california-street”
Failed to import Media “car-picjumbo-com”
Failed to import Media “front-of-san-francisco”
Failed to import Media “two-iconic-muni”
Failed to import Media “travel-blog-1”
Failed to import Media “travel-blog-2”
Failed to import Media “travel-blog-3”
Failed to import Media “travel-blog-4”
Failed to import Media “travel-blog-5”
Failed to import Media “viajar-com-os”
Failed to import Media “travel-blog”
Failed to import Media “travel-blog-6”
Failed to import Media “travel-blog-7”
Failed to import Media “travel-blog-8”
Failed to import Media “travel-blog-9”
Failed to import Media “travel-blog-10”
Failed to import Media “travel-blog-11”
Failed to import Media “slider-1.jpg”
Failed to import Media “slider-2.jpeg”
Failed to import Media “slider-3.jpeg”
Failed to import Media “slider-4.jpeg”
Failed to import Media “travel-shop-1”
Failed to import Media “travel-shop-4”
Failed to import Media “travel-shop-2”
Failed to import Media “travel-shop-3”
Failed to import Media “travel-shop-5”
Failed to import Media “travel-shop-6”
Failed to import Media “travel-shop-7”
Failed to import Media “travel-shop-8”
Failed to import Media “travel-shop-9”
Failed to import Media “icon-sale”
Failed to import Media “image-left-blog”
Failed to import Media “banner-html”
Failed to import Media “banner-home-2”
Failed to import Media “logo”
Failed to import Media “logo-footer”
Failed to import Media “slider-home3-1.jpg”
Failed to import Media “logo”
Failed to import Media “slider-home3-2”
Failed to import Media “slider-home3-3”