Windows 8.1 upgrade

Hi
am trying to upgrade my hp laptop windows 8 64 bit to windows 8.1 bit. I have used space 46.7gb. Free space 859. Gb capacity 905 gb memory ram 8.00gb when trying to upgrade to windows 8.1 I get windows 8.1 couldn't be installed. I have all the Microsoft windows updates I can not find any of the hidden updates if there is any. can anyone please tell me how install this ? Thank you