Update Manager Linux Mint 18 Cinnamon

How I can fix-it this message error:

Failed to fetch http://apt.insynchq.com/mint/dists/sarah/InRelease As seguintes assinaturas eram inválidas: KEYEXPIRED 1473479811 KEYEXPIRED 1473479811 KEYEXPIRED 1473479811 KEYEXPIRED 1473479811 KEYEXPIRED 1473479811 KEYEXPIRED 1473479811 KEYEXPIRED 1473479811

Thanks!

@Ruy_Sabino_Pereira: Very sorry for the trouble. Please try the instructions on this page: New Insync version: 1.3.11.