#4103 Debian Repository not signed

[Norbert E. Wagner]

apt update fails with the error:

W: GPG error: https://freefr.dl.sourceforge.net/project/jedit  Release: The following signatures were invalid: B4EC0C754740F62B7E257989E6A233DBE3AFBEFC
E: The repository 'https://freefr.dl.sourceforge.net/project/jedit  Release' is not signed.
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.

This is what I have in my sources file:
deb https://freefr.dl.sourceforge.net/project/jedit /

I did import the keys, but that is apparently not the problem. I presume the Release.gpg file is broken

I am using Linux Mint 19.3 which is based on Ubuntu Bionic

[Michael Sidenius (MTI)]

I see a related error, since the key for the repository is no longer present at: keyserver.ubuntu.com
(when manually looking up), so the command to add the key to your list of public keys will not work;
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E6A233DBE3AFBEFC
This a a basic error with the key not being available for download, and will hit any debian based distribution.