So, I went to download 1.12 and it gave this error:

Unable to save download. jopt-simple-5.0.3.jar
Name: jopt-simple-5.0.3.jar
URL: https://libraries.minecraft.net/net/sf/jopt-simple/jopt-simple/5.0.3/jopt-simple-5.0.3.jar
Error details: Attempting to move successful download to C:/Users\pc_user\AppData\Roaming\.minecraft\libraries\net/sf/jopt-simple/jopt-simple/5.0.3/jopt-simple-5.0.3.jar
The process cannot access the file because it is being used by another process
Filename on disk: 2624-23e2-a66d-6683
Path: C:\Users\pc_user\AppData\Local\Temp\2624-23e2-a66d-6683
Exists: file

PLEASE HELP ME!