Hello. I have ubuntu 18.4. On apt-get update is a error: $ sudo apt-get update Hit:1 http://de.archive.ubuntu.com/ubuntu bionic InRelease Hit:2 http://ppa.launchpad.net/freecad-maintainers/freecad-daily/ubuntu bionic InRelease Hit:3 http://de.archive.ubuntu.com/ubuntu bionic-updates InRelease Hit:4 http://de.archive.ubuntu.com/ubuntu bionic-backports InRelease Hit:5 http://ppa.launchpad.net/freecad-maintainers/freecad-stable/ubuntu bionic InRelease Hit:6 http://ppa.launchpad.net/js-reynaud/kicad-5/ubuntu bionic InRelease Get:7 http://security.ubuntu.com/ubuntu bionic-security InRelease [88.7 kB] Hit:8 http://ppa.launchpad.net/js-reynaud/kicad-5.1/ubuntu bionic InRelease Hit:9 http://ppa.launchpad.net/openscad/releases/ubuntu bionic InRelease Hit:10 http://ppa.launchpad.net/otter-browser/release/ubuntu bionic InRelease Get:11 http://mirror.ppa.trinitydesktop.org/trinity/deb/trinity-sb bionic InRelease [25.0 kB] Ign:12 http://mirror.ppa.trinitydesktop.org/trinity/deb/trinity-sb boinic InRelease Err:13 http://mirror.ppa.trinitydesktop.org/trinity/deb/trinity-sb boinic Release � 404� Not Found [IP: 37.205.10.16 80] Reading package lists... Done E: The repository 'http://mirror.ppa.trinitydesktop.org/trinity/deb/trinity-sb boinic Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. My package lists: $ cat /etc/apt/sources.list # deb cdrom:[Ubuntu 18.04 LTS _Bionic Beaver_ - Release amd64 (20180426)]/ bionic main restricted # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to # newer versions of the distribution. deb http://de.archive.ubuntu.com/ubuntu/ bionic main restricted # deb-src http://de.archive.ubuntu.com/ubuntu/ bionic main restricted ## Major bug fix updates produced after the final release of the ## distribution. deb http://de.archive.ubuntu.com/ubuntu/ bionic-updates main restricted # deb-src http://de.archive.ubuntu.com/ubuntu/ bionic-updates main restricted ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team. Also, please note that software in universe WILL NOT receive any ## review or updates from the Ubuntu security team. deb http://de.archive.ubuntu.com/ubuntu/ bionic universe # deb-src http://de.archive.ubuntu.com/ubuntu/ bionic universe deb http://de.archive.ubuntu.com/ubuntu/ bionic-updates universe # deb-src http://de.archive.ubuntu.com/ubuntu/ bionic-updates universe ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team, and may not be under a free licence. Please satisfy yourself as to ## your rights to use the software. Also, please note that software in ## multiverse WILL NOT receive any review or updates from the Ubuntu ## security team. deb http://de.archive.ubuntu.com/ubuntu/ bionic multiverse # deb-src http://de.archive.ubuntu.com/ubuntu/ bionic multiverse deb http://de.archive.ubuntu.com/ubuntu/ bionic-updates multiverse # deb-src http://de.archive.ubuntu.com/ubuntu/ bionic-updates multiverse ## N.B. software from this repository may not have been tested as ## extensively as that contained in the main release, although it includes ## newer versions of some applications which may provide useful features. ## Also, please note that software in backports WILL NOT receive any review ## or updates from the Ubuntu security team. deb http://de.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse # deb-src http://de.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse ## Uncomment the following two lines to add software from Canonical's ## 'partner' repository. ## This software is not part of Ubuntu, but is offered by Canonical and the ## respective vendors as a service to Ubuntu users. # deb http://archive.canonical.com/ubuntu bionic partner # deb-src http://archive.canonical.com/ubuntu bionic partner deb http://security.ubuntu.com/ubuntu bionic-security main restricted # deb-src http://security.ubuntu.com/ubuntu bionic-security main restricted deb http://security.ubuntu.com/ubuntu bionic-security universe # deb-src http://security.ubuntu.com/ubuntu bionic-security universe deb http://security.ubuntu.com/ubuntu bionic-security multiverse # deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse #################### # Trinity preliminary stable builds deb http://mirror.ppa.trinitydesktop.org/trinity/deb/trinity-sb bionic deps-r14 main-r14 deb-src http://mirror.ppa.trinitydesktop.org/trinity/deb/trinity-sb boinic deps-r14 main-r14 How can I solve the problem? Best regards