cannot load minecraft from launcher - unable to save download

Hi, when I select play from the launcher I get an error saying "unable to save download". details are below. I tried multiple things with no luck and no fix.
any help is greatly appreciated. thank you for your time.

Unable to save download. 1.8.json
Name: 1.8.json
URL: https://launchermeta.mojang.com/mc/assets/1.8/e264980ad255aad2174cbe4d674c102474ae5202/1.8.json
Error details: Attempting to move successful download to C:/Users\jemmm\AppData\Roaming\.minecraft\assets\indexes/1.8.json
The process cannot access the file because it is being used by another process
Filename on disk: 64d0-e023-1a3b-f103
Path: C:\Users\jemmm\AppData\Local\Temp\64d0-e023-1a3b-f103
Exists: file