Ign:30 http://ppa.launchpad.net/bzindovic/suitesparse-bugfix-1319687/ubuntu xenial/main i386 Packages
Ign:44 http://ppa.launchpad.net/bzindovic/suitesparse-bugfix-1319687/ubuntu xenial/main all Packages
Ign:48 http://ppa.launchpad.net/bzindovic/suitesparse-bugfix-1319687/ubuntu xenial/main Translation-en_US
Ign:57 http://ppa.launchpad.net/bzindovic/suitesparse-bugfix-1319687/ubuntu xenial/main Translation-en
Ign:60 http://ppa.launchpad.net/bzindovic/suitesparse-bugfix-1319687/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:61 http://ppa.launchpad.net/bzindovic/suitesparse-bugfix-1319687/ubuntu xenial/main DEP-11 64x64 Icons
Get:62 http://packages.ros.org/ros/ubuntu xenial/main i386 Packages [588 kB]
Fetched 11.4 MB in 2min 25s (78.4 kB/s)
AppStream cache update completed, but some metadata was ignored due to errors.
Reading package lists... Done
W: The repository 'http://ppa.launchpad.net/bzindovic/suitesparse-bugfix-1319687/ubuntu xenial Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://ppa.launchpad.net/bzindovic/suitesparse-bugfix-1319687/ubuntu/dists/xenial/main/binary-amd64/Packages 404 Not Found [IP: 91.189.95.83 80]
E: Some index files failed to download. They have been ignored, or old ones used instead
解决方式：
删除/etc/apt/sources.list.d目录下对应的文件
来源：https://blog.csdn.net/huoxingrenhdh/article/details/102706216