Can't check updates from App Center

Question

Everytime I open the App Center, this message would show up. What should I do to fix it? I'm on Juno, if that helps.

Edit: The error details are on Pastebin because StackExchange limits characters to 30000 characters or so. (https://pastebin.com/KNBxLt9z)

Answer 1

You have 2 issues here.

1. W: Target Packages * is configured multiple times in /etc/apt/sources.list...

Since you have issues in sources.list only, fixing this is easy. Follow one of the 3 methods to fix the issue:

1. Identify and delete duplicate entries: In your installation duplicate entries are at line 57, 68, 78, 62, 70, 80, 88, 98, 100 and 102. Run,

   sudo sed -i '57d;68d;78d;62d;70d;80d;88d;98d,100d;102d' /etc/apt/sources.list
   

2. Recreate sources.list: Delete old sources.list using sudo rm /etc/apt/sources.list. To recreate repository information you can either,

   • Go to software-properties-gtk, select components and save.

   OR

   • Since you need to restore default repository information in sources.list, you can do that by running:

     sudo nano /etc/apt/sources.list
     

   • Add these lines:

     deb http://archive.ubuntu.com/ubuntu/ bionic main restricted universe multiverse
     deb http://security.ubuntu.com/ubuntu/ bionic-security main restricted universe multiverse
     deb http://archive.ubuntu.com/ubuntu/ bionic-updates main restricted universe multiverse
     

   • Save using Ctrl+X followed by Y.

3. Follow David's Script

2. E: The repository * does not have a Release file.

Most of the repositories here in the error don't know "juno". You need to fix that. Either remove the repositories using Other Software tab in software-properties-gtk or if you want to use those PPA replace "juno" with "bionic" since juno is based on Ubuntu Bionic (18.04) and added repositories know what is bionic. To do so, follow either of the two methods.

• GUI method: Open software-properties-gtk, go to Other Software tab and edit the reposiories. Replace juno with bionic.

• CLI method: You can do this using sed, just run

  sudo sed -i 's/juno/bionic/g' /etc/apt/sources.list /etc/apt/sources.list.d/*
  

  and you're done.

Once you're done, run sudo apt update in terminal and try relaunching app center.