I cant play

Every time I open the launcher and click play it says this
Unable to save download. 1.12.2.jar
Name: 1.12.2.jar
URL: https://launcher.mojang.com/mc/game/1.12.2/client/0f275bc1547d01fa5f56ba34bdc87d981ee12daf/client.jar
Error details: Attempting to move successful download to C:/Users\darkt\AppData\Roaming\.minecraft\versions\1.12.2/1.12.2.jar
The process cannot access the file because it is being used by another process
Filename on disk: 9f8c-dd0e-f2a4-f0ba
Path: C:\Users\darkt\AppData\Local\Temp\9f8c-dd0e-f2a4-f0ba
Exists: false