Why is my client website not crawling propery and its cached version is showing error?

when I check the cached version of the site, it says "webcache.googleusercontent.com says: failed". It is showing the cached data but also this error. the website is dofollow and indexable. Please give suggestions what is the exact problem.

http://webcache.googleusercontent.com/search?q=cache%3Ahttps%3A%2F%2Fwww.omkarahills.com&rlz=1C1AVUC_enIN781IN782&oq=cache%3Ahttps%3A%2F%2Fwww.omkarahills.com&aqs=chrome..69i57j69i58.2267j0j4&sourceid=chrome&ie=UTF-8