W:The repository 'http://ppa.launchpad.net/tualatrix/next/ubuntu xenial Release' does not have a Release file.,
W:Data from such a repository can't be authenticated and is therefore potentially dangerous to use., W:See apt-secure(8) manpage for repository creation and user configuration details.,
E:Failed to fetch http://ppa.launchpad.net/tualatrix/next/ubuntu/dists/xenial/main/binary-amd64/Packages 404 Not Found,
E:Some index files failed to download. They have been ignored, or old ones used instead.
首先,这些大多是带有一个错误的警告。
如果您阅读它们,它会告诉您问题:
PPA 的维护者没有 xenial 的包。
任何一个
联系维护者 - https://launchpad.net/~tualatrix/+archive/ubuntu/next
禁用 PPA 并为您想要的软件包找到另一个来源。