How to install App Grid in Ubuntu 16.10

You aren't using 16.10 (Yakkety), you are using 17.04 (Zesty) which is still in development, not stable and not for normal users.

The PPA you have added does not support Zesty so the package will not install.

You could change the PPA source file and change the word "zesty" to "yakkety" and it will install

Not all PPAs support all releases.

I see several issues:

1. As already noted by actionparsnip, you are running Ubuntu 17.04 which is the version in development, to be published in April next year.

2. Several PPAs do not contain software for Ubuntu 17.04, and having them defined as repository source consequently gives 404 errors

3. You seem to have mistyped the ppa once, which created a wrong entry in a config file (http://ppa.appgrid/stable)

What is the output of the commands
grep appgrid /etc/apt/sources.list /etc/apt/sources.list.d/*.list
grep tualatrix /etc/apt/sources.list /etc/apt/sources.list.d/*.list

Thanks for your kind input. Actually I couldn't follow the instructions given earlier.
The output for the new commands is:

edmond@HP:~$ grep appgrid /etc/apt/sources.list /etc/apt/sources.list.d/*.list
/etc/apt/sources.list.d/appgrid-ubuntu-stable-zesty.list:deb http://ppa.appgrid/stable zesty main
/etc/apt/sources.list.d/appgrid-ubuntu-stable-zesty.list:deb http://ppa.launchpad.net/appgrid/stable/ubuntu zesty main
edmond@HP:~$ grep tualatrix /etc/apt/sources.list /etc/apt/sources.list.d/*.list/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:deb http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main
/etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list:# deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu zesty main

Issue the command
sudo gedit /etc/apt/sources.list.d/appgrid-ubuntu-stable-zesty.list
In the editor window that opens (probably after a request to enter your password as confirmation for an administrative action) do the following:
delete the line(s) that contain "ppa.appgrid"
In the line(s) with "ppa.launchpad.net/appgrid" change the word zesty into yakkety
save the file and close the editor

Issue the command
sudo gedit /etc/apt/sources.list.d/tualatrix-ubuntu-ppa-zesty.list
In the editor window that opens do the following:
delete all duplicate lines leaving just one with "deb" and one with "deb-src"
change the word zesty into trusty
save the file and close the editor

Finally re-issue the command

sudo apt-get update

and report the results.

Note: You still have to be aware that the development version of Ubuntu is highly instable and may show all kinds of problems during its development period. Why did you upgrade to that version at all?

The new output results are:

edmond@HP:~$ sudo apt-get update
Get:1 http://ppa.launchpad.net/appgrid/stable/ubuntu yakkety InRelease [17.6 kB]
Get:2 http://archive.ubuntu.com/ubuntu zesty InRelease [253 kB]
Ign:3 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty InRelease
Get:4 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty Release [14.0 kB]
Ign:5 http://archive.canonical.com/ubuntu trusty InRelease
Get:7 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty Release.gpg [316 B]
Hit:8 http://archive.canonical.com/ubuntu trusty Release
Ign:9 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:10 http://dl.google.com/linux/chrome/deb stable Release
Get:11 http://archive.ubuntu.com/ubuntu zesty-updates InRelease [102 kB]
Get:12 http://archive.ubuntu.com/ubuntu zesty-backports InRelease [102 kB]
Get:13 http://ppa.launchpad.net/appgrid/stable/ubuntu yakkety/main i386 Packages [580 B]
Get:14 http://archive.ubuntu.com/ubuntu zesty-security InRelease [102 kB]
Get:15 http://ppa.launchpad.net/appgrid/stable/ubuntu yakkety/main amd64 Packages [580 B]
Get:16 http://ppa.launchpad.net/appgrid/stable/ubuntu yakkety/main Translation-en [412 B]
Hit:6 http://screenshots.getdeb.net yakkety-getdeb InRelease
Get:17 http://archive.ubuntu.com/ubuntu zesty-proposed InRelease [102 kB]
Ign:7 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty Release.gpg
Get:18 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty/main i386 Packages [707 B]
Get:19 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty/main amd64 Packages [707 B]
Get:21 http://archive.canonical.com/ubuntu trusty/partner Sources [10.0 kB]
Get:23 http://archive.ubuntu.com/ubuntu zesty/main Sources [907 kB]
Get:24 http://archive.ubuntu.com/ubuntu zesty/universe Sources [8,293 kB]
Get:25 http://screenshots.getdeb.net yakkety-getdeb/apps Sources [54.4 kB]
Get:26 http://archive.ubuntu.com/ubuntu zesty/main i386 Packages [1,227 kB]
Get:27 http://archive.ubuntu.com/ubuntu zesty/main amd64 Packages [1,231 kB]
Get:28 http://archive.ubuntu.com/ubuntu zesty/main Translation-en [584 kB]
Get:29 http://archive.ubuntu.com/ubuntu zesty/main amd64 DEP-11 Metadata [575 kB]
Get:30 http://archive.ubuntu.com/ubuntu zesty/main DEP-11 64x64 Icons [375 kB]
Get:31 http://archive.ubuntu.com/ubuntu zesty/universe i386 Packages [7,911 kB]
Get:32 http://archive.ubuntu.com/ubuntu zesty/universe amd64 Packages [7,928 kB]
Get:33 http://archive.ubuntu.com/ubuntu zesty/universe Translation-en [4,596 kB]
Get:34 http://archive.ubuntu.com/ubuntu zesty/universe amd64 DEP-11 Metadata [2,529 kB]
Get:35 http://archive.ubuntu.com/ubuntu zesty/universe DEP-11 64x64 Icons [7,541 kB]
Get:36 http://archive.ubuntu.com/ubuntu zesty/multiverse amd64 DEP-11 Metadata [44.2 kB]
Get:37 http://archive.ubuntu.com/ubuntu zesty/multiverse DEP-11 64x64 Icons [196 kB]
Get:38 http://archive.ubuntu.com/ubuntu zesty-updates/main amd64 DEP-11 Metadata [208 B]
Get:39 http://archive.ubuntu.com/ubuntu zesty-updates/universe amd64 DEP-11 Metadata [212 B]
Get:40 http://archive.ubuntu.com/ubuntu zesty-updates/multiverse amd64 DEP-11 Metadata [212 B]
Get:41 http://archive.ubuntu.com/ubuntu zesty-backports/main amd64 DEP-11 Metadata [208 B]
Get:42 http://archive.ubuntu.com/ubuntu zesty-backports/universe amd64 DEP-11 Metadata [212 B]
Get:43 http://archive.ubuntu.com/ubuntu zesty-backports/multiverse amd64 DEP-11 Metadata [212 B]
Get:44 http://archive.ubuntu.com/ubuntu zesty-security/main amd64 DEP-11 Metadata [204 B]
Get:45 http://archive.ubuntu.com/ubuntu zesty-security/universe amd64 DEP-11 Metadata [208 B]
Get:46 http://archive.ubuntu.com/ubuntu zesty-security/multiverse amd64 DEP-11 Metadata [208 B]
Get:47 http://archive.ubuntu.com/ubuntu zesty-proposed/universe i386 Packages [538 kB]
Get:48 http://archive.ubuntu.com/ubuntu zesty-proposed/universe amd64 Packages [560 kB]
Get:49 http://archive.ubuntu.com/ubuntu zesty-proposed/universe Translation-en [297 kB]
Get:50 http://archive.ubuntu.com/ubuntu zesty-proposed/universe amd64 DEP-11 Metadata [179 kB]
Get:51 http://archive.ubuntu.com/ubuntu zesty-proposed/universe DEP-11 64x64 Icons [488 kB]
Get:52 http://archive.ubuntu.com/ubuntu zesty-proposed/multiverse amd64 DEP-11 Metadata [6,596 B]
Get:53 http://archive.ubuntu.com/ubuntu zesty-proposed/main amd64 Packages [132 kB]
Get:54 http://archive.ubuntu.com/ubuntu zesty-proposed/main i386 Packages [131 kB]
Get:55 http://archive.ubuntu.com/ubuntu zesty-proposed/main Translation-en [61.7 kB]
Get:56 http://archive.ubuntu.com/ubuntu zesty-proposed/main amd64 DEP-11 Metadata [139 kB]
Get:57 http://archive.ubuntu.com/ubuntu zesty-proposed/main DEP-11 64x64 Icons [111 kB]
Fetched 47.3 MB in 31s (1,489 kB/s)
Reading package lists... Done
W: GPG error: http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty Release: The following signatures were invalid: FE85409EEAB40ECCB65740816AF0E1940624A220
W: The repository 'http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty Release' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details

What do you get for the commands

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 0624A220
sudo apt-get update

These commands give the output:

edmond@HP:~$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 0624A220
[sudo] password for edmond:
Executing: /tmp/tmp.fJ2smEN7G0/gpg.1.sh --keyserver keyserver.ubuntu.com --recv-keys 0624A220
gpg: key 6AF0E1940624A220: "Launchpad PPA for TualatriX" not changed
gpg: Total number processed: 1
gpg: unchanged: 1
edmond@HP:~$ sudo apt-get update
Hit:1 http://ppa.launchpad.net/appgrid/stable/ubuntu yakkety InRelease
Ign:2 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty InRelease
Get:3 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty Release [14.0 kB]
Ign:4 http://archive.canonical.com/ubuntu trusty InRelease
Hit:5 http://archive.ubuntu.com/ubuntu zesty InRelease
Hit:6 http://archive.canonical.com/ubuntu trusty Release
Hit:7 http://archive.ubuntu.com/ubuntu zesty-updates InRelease
Get:8 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty Release.gpg [316 B]
Hit:9 http://archive.ubuntu.com/ubuntu zesty-backports InRelease
Hit:11 http://archive.ubuntu.com/ubuntu zesty-security InRelease
Hit:12 http://archive.ubuntu.com/ubuntu zesty-proposed InRelease
Ign:13 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:14 http://dl.google.com/linux/chrome/deb stable Release
Hit:10 http://screenshots.getdeb.net yakkety-getdeb InRelease
Ign:8 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty Release.gpg
Hit:16 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty/main i386 Packages
Ign:16 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty/main i386 Packages
Hit:17 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty/main amd64 Packages
Ign:17 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty/main amd64 Packages
Hit:16 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty/main i386 Packages
Hit:17 http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty/main amd64 Packages
Fetched 14.3 kB in 2s (5,036 B/s)
Reading package lists... Done
W: GPG error: http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty Release: The following signatures were invalid: FE85409EEAB40ECCB65740816AF0E1940624A220
W: The repository 'http://ppa.launchpad.net/tualatrix/ppa/ubuntu trusty Release' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.

I am sorry, but I do not know the cause of that "signatures were invalid" error.

In my opinion it does not make sense to run Ubuntu 17.04 if you are not able to cope with problems yourself.
The Launchpad answer area is not meant for support of a future Ubuntu release, but only for current versions.
If you detect a function in the development version, that does not work as designed, you should create a bug report to discuss that with the developers.

You should consider deleting your Ubuntu system (of course only after creating backup copies of your files) and re-starting with a clean installation of Ubuntu 16.04 (supported until April 2021).

That is what I was going to write. I suggest a clean install of Xenial. It will act and run as you expect

Thank you.

Just realised that I am runninig Ubuntu 16.10 although the output of lsb_release -a shows:

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu Zesty Zapus (development branch)
Release: 17.04
Codename: zesty

This is confirmed in the menu for Details in System Settings.

After running
sudo add-apt-repository ppa:appgrid/stable
sudo apt-get update

the output for: sudo apt-get install appgrid is E: Unable to locate package appgrid.

Also there is the error message
'50unattended-upgrades.ucf-dist' in directory '/etc/apt/apt.conf.d/' as it has an invalid filename extension

The warning about '50unattended-upgrades.ucf-dist' is easy to remedy, just delete that file
sudo rm /etc/apt/apt.conf.d/50unattended-upgrades.ucf-dist

What are you taking as basis for your statement that you are running Ubuntu 16.10?
The output of lsb_release -a shows 17.04, and the version reference in most of the lines for sudo apt-get update shows "zesty"!

Also that message "Unable to locate package appgrid" is caused by the fact that you are running Ubuntu 17.04.
https://launchpad.net/~appgrid/+archive/ubuntu/stable/+packages shows that an appgrid package is available for 14.04, 16.04 and 16.10 (trusty, xenial and yakkety) but not for 17.04 (zesty).

I deleted the previous Ubuntu 16.10 partition and then reinstalled Ubuntu 16.04. after that I did an upgrade to 16.10, Even now the output from lsb_release -a shows:
         No LSB modules are available.
         Distributor ID: Ubuntu
         Description: Ubuntu Zesty Zapus (development branch)
         Release: 17.04
        Codename: zesty

However, In System Settings in the Overview of Details it shows Ubuntu 16.10

What is the output of the commands

cat /etc/issue
cat /etc/lsb-release
apt-cache policy base-files

?

The output is as follows:
 cat /etc/issue:
Ubuntu Yakety Yak (development branch) \n \l

 cat /etc/lsb-release:
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.10
DISTRIB_CODENAME=yakkety
DISTRIB_DESCRIPTION=Yakkety Yak

 apt-cache policy base-files:
base-files:
  Installed: 9.6ubuntu7
  Candidate: 9.6ubuntu7
  Version table:
 *** 9.6ubuntu7 500
        500 http://archive.ubuntu.com/ubuntu zesty/main amd64 Packages
        100 /var/lib/dpkg/status

This is a strange and unhealthy hybrid between yakkety and zesty (16.10 and 17.04).

The installed package base-files 9.6ubuntu7 provides a file /etc/issue with the contents of
"Ubuntu Zesty Zapus (development branch) \n \l"
but your system's file contains
"Ubuntu Yakety Yak (development branch) \n \l"
even with a typo error!

How is that possible?

The only recommendation that I can give is scrapping the system and starting with a clean new installation.

 Thanks for the help.