the Hide wrote...
Who should I contact regarding the following error
E: Malformed entry 5 in list file /etc/apt/sources.list.d/additional-repositories.list (Component) E: The list of sources could not be read. E: _cache->open() failed, please report.
Assuming you're using Debian and not some derivatve: Some Debian users mailing list, like https://lists.debian.org/debian-user/
From the above error message I assume there's a format error in /etc/apt/sources.list.d/additional-repositories.list - so it was wise to include the content of that file in a message to that list.
If it's actually a bug in apt, the Debian bug tracker was the place to go. This list here however is about development of the Linux kernel, the stable releases, so not quite the right place.
Christoph