remove sources .list and index.html in /etc/apt dir
# cp /etc/apt/preferences.d/index.html /tmp
# rm -rf /etc/apt/preferences.d/index.html
#cp /etc/apt/sources.list /tmp
# rm -rf sources.list
then reboot
This will help us understand what in your sources.list is having issues.
apt-get update
Err:1 http://ftp.harukasan.org/kali kali-rolling InRelease
The following signatures were invalid: EXPKEYSIG ED444FF07D8D0BF6 Kali Linux Repository
Reading package lists... Done
W: GPG error: http://ftp.harukasan.org/kali kali-rolling InRelease: The following signatures were invalid: EXPKEYSIG ED444FF07D8D0BF6 Kali Linux Repository
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.
It looks like you are running Kali not Ubuntu MATE
You will probably find more specific support at the Kali forums
However, the error you are having looks to be an improper gpg key that you would need to update to the correct one that Kali uses to sign their packages.
Good luck
N: Ignoring file 'apt.strace' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
E: The repository 'http://ppa.launchpad.net/webupd8team/sublime-text-3/ubuntu bionic 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.
Kindly,, i face this Error with Bash - Windows 10
could u please assist
please i'm having this same issue
i need help
please i having an issue with my ubuntu.
See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: http://ftp.us.debian.org/debian stretch Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7638D0442B90D010 NO_PUBKEY 04EE7237B7D453EC NO_PUBKEY EF0F382A1A7B6500
E: The repository 'http://ftp.us.debian.org/debian stretch 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.
sirhezzy@linux:~$
what should i do?4
See post's #2 and #3 and follow those steps.
i have same issue and followed steps but still having issue
......... Reading package lists... Done
W: GPG error: //http://repo.mongodb.org/apt/ubuntu precise/mongodb-org/3.0 Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9ECBEC467F0CEB10
E: The repository '//http://repo.mongodb.org/apt/ubuntu precise/mongodb-org/3.0 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.
N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository '//http://repo.mongodb.org/apt/debian buster/mongodb-org/4.2 InRelease' doesn't support architecture 'i386'
N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository '//http://repo.mongodb.org/apt/debian buster/mongodb-org/4.4 InRelease' doesn't support architecture 'i386'
I am getting this error. Please do help me, tried all the possible ways
Welcome, @Moni_Shankar!
No offense, but there's so many things wrong here that it's hard for me to decide what to bring up first.
First, you didn't tell us what distribution you are using. Tell us the distribution (example: "Ubuntu MATE"), and the version (example: "20.04.1" or "focal").
Second, it's very weird that you seem to have PPAs for MongoDB intended for both Debian Buster and Ubuntu 12.04. What kind of system is this?
Third, there's many changes you should probably make to your /etc/apt/sources.list file, most notably the // preceding the http:// part of each URL should be removed. There is no reason to keep it there, I believe.
Finally, why do you want to install MongoDB 3.0 and 4.4? And it looks like the MongoDB packages are built for amd64 and i386 architectures but the repositories only expose the amd64 packages; if you're actually using an i386 system, contact the MongoDB developers about this weirdness. And if you're using amd64, change the i386 in the sources.list to amd64.
Again, please give us information about your setup like I asked for above. But you can in addition try the suggestions I made.
Hi @gordon
Thanks for replying, let me share you the details as u asked
1.The distribution is
Linux mx 4.19.0-14-amd64 #1 SMP Debian 4.19.171-2 (2021-01-30) x86_64 GNU/Linux.
2.Its a debian buster Debian GNU/Linux 10 (buster).
3.I added // because this community was not allowing me to post more than 2 links as I am new here, so I commented out this hyperlinks.
My main aim is to install mongodb and start the server and store some dummy data for my application.
Thanks in advance.
Oh, OK. Now I understand the //.
Well, my suggestion is to eliminate the line in your sources.list file (or it might be a file under /etc/apt/sources.list.d) for Ubuntu Precise. I'm guessing that line will look like: deb http://repo.mongodb.org/apt/ubuntu precise mongodb-org, or something similar.
That leaves you with the line for Debian Buster. Find that line and replace any instance of "i386" with "amd64". Save the sources.list file, then do another apt update.
Hopefully that'll get you somewhere.
You sound like you are a pro so I’m gonna use that 
I’m just getting started and trying to install noetic and gazebo. At the beginning of the installation steps when I enter sudo apt update then I get the message. Do I have to do something before installation? I just installed Ubuntu and get stuck.
Hi, people...im trying to install PHP 8 on ubuntu 20.04 but now when i install ppa, its result on this Error. please help
Reading package lists... Done
W: GPG error: https://dl.winehq.org/wine-builds/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 76F1A20FF987672F
E: The repository 'https://dl.winehq.org/wine-builds/ubuntu focal InRelease' 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.
W: GPG error: http://ppa.launchpad.net/numix/ppa/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 52B709720F164EEB
E: The repository 'http://ppa.launchpad.net/numix/ppa/ubuntu focal InRelease' 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.
W: GPG error: http://security.ubuntu.com/ubuntu focal-security InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://security.ubuntu.com/ubuntu focal-security InRelease' 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal InRelease' 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal-updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal-updates InRelease' 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.
W: GPG error: http://ppa.launchpad.net/papirus/papirus/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E58A9D36647CAE7F
E: The repository 'http://ppa.launchpad.net/papirus/papirus/ubuntu focal InRelease' 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.
E: The repository 'http://ppa.launchpad.net/noobslab/icons2/ubuntu focal 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal-backports InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal-backports InRelease' 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal-proposed InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal-proposed InRelease' 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.
E: The repository 'http://ppa.launchpad.net/snwh/pulp/ubuntu focal 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.
E: The repository 'http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu focal 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.Preformatted textHere is full log after running : sudo add-apt-repository ppa:ondrej/php
imsamaritan@imsamaritan-Lenovo-G40-30:/var/lib/apt$ sudo add-apt-repository ppa:ondrej/php
Co-installable PHP versions: PHP 5.6, PHP 7.x and most requested extensions are included. Only Supported Versions of PHP (http://php.net/supported-versions.php) for Supported Ubuntu Releases (https://wiki.ubuntu.com/Releases) are provided. Don't ask for end-of-life PHP versions or Ubuntu release, they won't be provided.
Debian oldstable and stable packages are provided as well: https://deb.sury.org/#debian-dpa
You can get more information about the packages at https://deb.sury.org
IMPORTANT: The <foo>-backports is now required on older Ubuntu releases.
BUGS&FEATURES: This PPA now has a issue tracker:
https://deb.sury.org/#bug-reporting
CAVEATS:
1. If you are using php-gearman, you need to add ppa:ondrej/pkg-gearman
2. If you are using apache2, you are advised to add ppa:ondrej/apache2
3. If you are using nginx, you are advised to add ppa:ondrej/nginx-mainline
or ppa:ondrej/nginx
PLEASE READ: If you like my work and want to give me a little motivation, please consider donating regularly: https://donate.sury.org/
WARNING: add-apt-repository is broken with non-UTF-8 locales, see
https://github.com/oerdnj/deb.sury.org/issues/56 for workaround:
# LC_ALL=C.UTF-8 add-apt-repository ppa:ondrej/php
More info: https://launchpad.net/~ondrej/+archive/ubuntu/php
Press [ENTER] to continue or Ctrl-c to cancel adding it.
Get:1 https://dl.winehq.org/wine-builds/ubuntu focal InRelease [8,041 B]
Ign:2 http://ppa.launchpad.net/noobslab/icons2/ubuntu focal InRelease
Err:1 https://dl.winehq.org/wine-builds/ubuntu focal InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 76F1A20FF987672F
Hit:3 https://deb.nodesource.com/node_16.x focal InRelease
Get:4 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]
Hit:5 http://ppa.launchpad.net/ondrej/php/ubuntu focal InRelease
Get:6 http://us.archive.ubuntu.com/ubuntu focal InRelease [265 kB]
Err:4 http://security.ubuntu.com/ubuntu focal-security InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
Ign:7 http://ppa.launchpad.net/snwh/pulp/ubuntu focal InRelease
Get:8 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]
Err:6 http://us.archive.ubuntu.com/ubuntu focal InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
Ign:9 http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu focal InRelease
Get:10 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease [108 kB]
Err:8 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
Err:11 http://ppa.launchpad.net/noobslab/icons2/ubuntu focal Release
404 Not Found [IP: 91.189.95.85 80]
Get:12 http://us.archive.ubuntu.com/ubuntu focal-proposed InRelease [267 kB]
Err:10 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
Get:13 http://ppa.launchpad.net/numix/ppa/ubuntu focal InRelease [17.5 kB]
Err:12 http://us.archive.ubuntu.com/ubuntu focal-proposed InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
Get:14 http://ppa.launchpad.net/papirus/papirus/ubuntu focal InRelease [18.0 kB]
Err:13 http://ppa.launchpad.net/numix/ppa/ubuntu focal InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 52B709720F164EEB
Err:15 http://ppa.launchpad.net/snwh/pulp/ubuntu focal Release
404 Not Found [IP: 91.189.95.85 80]
Err:14 http://ppa.launchpad.net/papirus/papirus/ubuntu focal InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E58A9D36647CAE7F
Err:16 http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu focal Release
404 Not Found [IP: 91.189.95.85 80]
Reading package lists... Done
W: GPG error: https://dl.winehq.org/wine-builds/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 76F1A20FF987672F
E: The repository 'https://dl.winehq.org/wine-builds/ubuntu focal InRelease' 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.
W: GPG error: http://security.ubuntu.com/ubuntu focal-security InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://security.ubuntu.com/ubuntu focal-security InRelease' 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal InRelease' 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal-updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal-updates InRelease' 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.
E: The repository 'http://ppa.launchpad.net/noobslab/icons2/ubuntu focal 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal-backports InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal-backports InRelease' 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal-proposed InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal-proposed InRelease' 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.
W: GPG error: http://ppa.launchpad.net/numix/ppa/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 52B709720F164EEB
E: The repository 'http://ppa.launchpad.net/numix/ppa/ubuntu focal InRelease' 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.
E: The repository 'http://ppa.launchpad.net/snwh/pulp/ubuntu focal 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.
W: GPG error: http://ppa.launchpad.net/papirus/papirus/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E58A9D36647CAE7F
E: The repository 'http://ppa.launchpad.net/papirus/papirus/ubuntu focal InRelease' 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.
E: The repository 'http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu focal 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.Here is full log after running : sudo apt install
imsamaritan@imsamaritan-Lenovo-G40-30:/var/lib/apt$ sudo add-apt-repository ppa:ondrej/php
Co-installable PHP versions: PHP 5.6, PHP 7.x and most requested extensions are included. Only Supported Versions of PHP (http://php.net/supported-versions.php) for Supported Ubuntu Releases (https://wiki.ubuntu.com/Releases) are provided. Don't ask for end-of-life PHP versions or Ubuntu release, they won't be provided.
Debian oldstable and stable packages are provided as well: https://deb.sury.org/#debian-dpa
You can get more information about the packages at https://deb.sury.org
IMPORTANT: The <foo>-backports is now required on older Ubuntu releases.
BUGS&FEATURES: This PPA now has a issue tracker:
https://deb.sury.org/#bug-reporting
CAVEATS:
1. If you are using php-gearman, you need to add ppa:ondrej/pkg-gearman
2. If you are using apache2, you are advised to add ppa:ondrej/apache2
3. If you are using nginx, you are advised to add ppa:ondrej/nginx-mainline
or ppa:ondrej/nginx
PLEASE READ: If you like my work and want to give me a little motivation, please consider donating regularly: https://donate.sury.org/
WARNING: add-apt-repository is broken with non-UTF-8 locales, see
https://github.com/oerdnj/deb.sury.org/issues/56 for workaround:
# LC_ALL=C.UTF-8 add-apt-repository ppa:ondrej/php
More info: https://launchpad.net/~ondrej/+archive/ubuntu/php
Press [ENTER] to continue or Ctrl-c to cancel adding it.
Get:1 https://dl.winehq.org/wine-builds/ubuntu focal InRelease [8,041 B]
Ign:2 http://ppa.launchpad.net/noobslab/icons2/ubuntu focal InRelease
Err:1 https://dl.winehq.org/wine-builds/ubuntu focal InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 76F1A20FF987672F
Hit:3 https://deb.nodesource.com/node_16.x focal InRelease
Get:4 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]
Hit:5 http://ppa.launchpad.net/ondrej/php/ubuntu focal InRelease
Get:6 http://us.archive.ubuntu.com/ubuntu focal InRelease [265 kB]
Err:4 http://security.ubuntu.com/ubuntu focal-security InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
Ign:7 http://ppa.launchpad.net/snwh/pulp/ubuntu focal InRelease
Get:8 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]
Err:6 http://us.archive.ubuntu.com/ubuntu focal InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
Ign:9 http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu focal InRelease
Get:10 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease [108 kB]
Err:8 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
Err:11 http://ppa.launchpad.net/noobslab/icons2/ubuntu focal Release
404 Not Found [IP: 91.189.95.85 80]
Get:12 http://us.archive.ubuntu.com/ubuntu focal-proposed InRelease [267 kB]
Err:10 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
Get:13 http://ppa.launchpad.net/numix/ppa/ubuntu focal InRelease [17.5 kB]
Err:12 http://us.archive.ubuntu.com/ubuntu focal-proposed InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
Get:14 http://ppa.launchpad.net/papirus/papirus/ubuntu focal InRelease [18.0 kB]
Err:13 http://ppa.launchpad.net/numix/ppa/ubuntu focal InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 52B709720F164EEB
Err:15 http://ppa.launchpad.net/snwh/pulp/ubuntu focal Release
404 Not Found [IP: 91.189.95.85 80]
Err:14 http://ppa.launchpad.net/papirus/papirus/ubuntu focal InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E58A9D36647CAE7F
Err:16 http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu focal Release
404 Not Found [IP: 91.189.95.85 80]
Reading package lists... Done
W: GPG error: https://dl.winehq.org/wine-builds/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 76F1A20FF987672F
E: The repository 'https://dl.winehq.org/wine-builds/ubuntu focal InRelease' 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.
W: GPG error: http://security.ubuntu.com/ubuntu focal-security InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://security.ubuntu.com/ubuntu focal-security InRelease' 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal InRelease' 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal-updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal-updates InRelease' 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.
E: The repository 'http://ppa.launchpad.net/noobslab/icons2/ubuntu focal 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal-backports InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal-backports InRelease' 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.
W: GPG error: http://us.archive.ubuntu.com/ubuntu focal-proposed InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
E: The repository 'http://us.archive.ubuntu.com/ubuntu focal-proposed InRelease' 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.
W: GPG error: http://ppa.launchpad.net/numix/ppa/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 52B709720F164EEB
E: The repository 'http://ppa.launchpad.net/numix/ppa/ubuntu focal InRelease' 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.
E: The repository 'http://ppa.launchpad.net/snwh/pulp/ubuntu focal 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.
W: GPG error: http://ppa.launchpad.net/papirus/papirus/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E58A9D36647CAE7F
E: The repository 'http://ppa.launchpad.net/papirus/papirus/ubuntu focal InRelease' 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.
E: The repository 'http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu focal 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.anyone still having that said error.
simply right-click desktop open as root. then open file system, /etc/apt/sources.list
then delete the file sources.list.
sudo apt-get full-update or sudo upgrade then u are good to go
Thank you!! Very much appreciated getting rid of that annoying error
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