I am trying to run sudo apt-get update
and running in these kinds of errors.
N: Ignoring file 'libjpeg8_8c-2ubuntu8_amd64.deb' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'libdouble-conversion1_3.1.0-3_amd64.deb' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'libjpeg-turbo8_2.0.3-0ubuntu1_amd64.deb' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
E: The repository 'http://ppa.launchpad.net/danielrichter2007/grub-customizer/ubuntu focal 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.
.deb
files simply don't belong in the/etc/apt/sources.list.d/
directory - move them somewhere else or remove them. The other issue has been addressed many times e.g. What can I do if a repository/PPA does not have a Release file? – steeldriver Oct 23 '20 at 15:41