when i try to load up minecraft it just says error and i try unistalling and reinstalling and nothing works

all it says is.
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\Caden Kennedy\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: 2593-9947-9631-47d4
Path: C:\Users\CADENK~1\AppData\Local\Temp\2593-9947-9631-47d4
Exists: file
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