Plesk Update or apt-get update error: The repository is no longer signed – Target Packages is configured multiple times

Symptoms

• The following error is received while doing Plesk Update or running "apt-get update" command:

  E: Failed to fetch http://autoinstall.plesk.com/PSA_18.0.34/dists/bionic/InRelease 403 Forbidden [IP: 192.168.100.100] E: The repository 'http://autoinstall.plesk.com/PSA_18.0.34 bionic InRelease' is no longer signed. W: Target Packages (all/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:9 and /etc/apt/sources.list.d/plesk.list:7 W: Target Packages (all/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:9 and /etc/apt/sources.list.d/plesk.list:7...

• A repository for an older version of Plesk is found listed on the Aptitude source files while the repository for the current version is also present:

  # grep -r PSA /etc/apt/sources*
  /etc/apt/sources.list:deb http://autoinstall.plesk.com/PSA_18.0.34/ bionic all
  /etc/apt/sources.list.d/plesk.list:deb http://autoinstall.plesk.com/pool/PSA_18.0.40_8022/ bionic extras

Cause

Leftover old repository no longer signed is present on the OS Aptitude sources and this produces part of the error. There are two Plesk repositories set for different versions and this is found as duplicated Target Packages.

Resolution

1. Connect to the server via SSH.

2. Create a copy of the current /etc/apt/sources.list file:

   # cp /etc/apt/sources.list{,.bak}

3. Edit to comment with preceding "#" or remove the line for the old repository found at /etc/apt/sources.list:

   # vi /etc/apt/sources.list

   deb http://archive.ubuntu.com/ubuntu bionic main restricted universe
   deb http://archive.ubuntu.com/ubuntu bionic-updates main restricted universe
   deb http://security.ubuntu.com/ubuntu bionic-security main restricted universe multiverse
   #deb http://autoinstall.plesk.com/PSA_18.0.34/ bionic all

4. Run apt-get update.

   # apt-get update