difficulties with ppa.launchpad.net/lyx-devel/release/ubuntu eoan

[Wolfgang Engelmann]

Hello,

I got this error

sudo dpkg --configure -a
dpkg: Fehler: dpkg frontend lock ist von einem anderen Prozess gesperrt

and the following command points to the 
ppa.launchpad.net/lyx-devel/release/ubuntu eoan

should I remove it from the sources.list (and if needed replace it by 
something better)? Wolfgang

$ sudo rm /var/lib/apt/lists/lock
wolfgang at Fuji:~/Schreibtisch/CV-we$ LC_ALL=C sudo apt update
Hit:1 http://security.debian.org/debian-security buster/updates InRelease
Ign:2 http://ppa.launchpad.net/lyx-devel/release/ubuntu eoan InRelease
Hit:3 http://ftp.de.debian.org/debian buster InRelease
Hit:4 http://ftp.de.debian.org/debian buster-updates InRelease
Err:5 http://ppa.launchpad.net/lyx-devel/release/ubuntu eoan Release
   404  Not Found [IP: 91.189.95.83 80]
Hit:6 http://ftp.de.debian.org/debian sid InRelease
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/lyx-devel/release/ubuntu 
eoan 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.