Cant launch the game... it says error, files missing. (see environment)

minecraft gives an error message....

Name: authlib-1.5.24.jar
URL: https://libraries.minecraft.net/com/mojang/authlib/1.5.24/authlib-1.5.24.jar
Error details: Request error -100: ERR_CONNECTION_CLOSED
Filename on disk: authlib-1.5.24.jar
Path: /Users/Danica/Library/Application Support/minecraft/libraries/com/mojang/authlib/1.5.24/authlib-1.5.24.jar
Exists: false
Copy to clipboard