Unpacker Error

I have played with .bak edited but when the game updated to 1.8.3 and i tried to unpack the new .pak file , in the half of progress the program gives me a error like "External error"


Can someone explain to me how to pass this?

reinstall the game through steam and re-unpack the game after

I tried to reinstall but when i try to unpack this error appeared

imgu r. com/ky xjc4l