Signatures not verified [duplicate]

Something's gone wrong with your apt keys or adding/changing repos or something... I don't know what

• What did you do that caused these errors, and what fixes have you tried?

But here are some band-aid solutions for your symptoms:

To just add the missing keys, this command should work (replace the "2EA8..." string with your acutal missing keys)

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 2EA8F35793D8809A

May try --keyserver keys.gnupg.net if any aren't on ubuntu
[see https://askubuntu.com/a/141088/129271 ]

It looked kind of like you didn't add some PPA's correctly, according to Ubuntu's instructions it should "fetch the PPA's key" by itself. Here's the terminal directions from https://help.ubuntu.com/community/Repositories/Ubuntu

Step 2: Open a terminal and enter:

$ sudo add-apt-repository ppa:user/ppa-name

Replace 'ppa:user/ppa-name' with the PPA's location that you noted above.

Your system will now fetch the PPA's key. This enables your Ubuntu system to verify that the packages in the PPA have not been interfered with since they were built.

In case there's a problem with your software sources, this should restore them to their "defaults". I'd make a backup copy of everything in /ect/apt/sources.list and /ect/apt/sources.list.d/ first, just in case. Not knowing what your Ubuntu version is I'm not sure what the "defaults" should be, or whether you've added extra PPA's or other sources. Running lsb_release -a should tell you about your version & "codename"

Backup the sources.list files

Just copy them to a backup folder somewhere, this should work:

sudo mv /etc/apt/sources.list /etc/apt/sources.list.old
sudo mv /etc/apt/sources.list.d /etc/apt/sources.list.d.old

Restoring the default Ubuntu sources.list

• For Ubuntu, if you do this it should generate a new fresh sources.list file

  1. delete the old files (sudo rm /etc/apt/sources.list and sudo rm -R /etc/apt/sources.list.d but BACKUP FIRST).

  2. Then do either of:

     • Run the Software Sources (sudo software-properties-gtk or sudo software-sources) select/check-mark some repos, pick a server and update.

     • Generate a new one at http://repogen.simplylinux.ch/ using your version & country (to pick local mirrors), then copy & paste it into your new sources.list with gksudo gedit /etc/apt/sources.list or in a terminal sudo nano /etc/apt/sources.list

The site http://repogen.simplylinux.ch/ has a LOT of optional PPA's too, looks quite useful. [courtesy How do I restore the default repositories? ]

After coming to know that apt can't handle more than 40 keys I started deleting ppa's and their keys from /etc/apt/trusted.gpg.d

After doing that I updated apt-cache and my problems were solved.