Error during update

A problem occurred during the update. This is usually some sort of network problem, please check your network connection and retry.

W:Failed to fetch http://archive.canonical.com/ubuntu/dists/xenial/partner/binary-amd64/Packages  Hash Sum mismatch
, W:Failed to fetch http://archive.canonical.com/ubuntu/dists/xenial/partner/binary-i386/Packages  Hash Sum mismatch
, W:Failed to fetch http://ftp.hawo.stw.uni-erlangen.de/ubuntu/dists/xenial-updates/main/binary-amd64/Packages  Hash Sum mismatch
, E:Some index files failed to download. They have been ignored, or old ones used instead.