XnView Software

The .deb package cannot be installed on a Lubuntu 20 ( I guess it's the same in Ubuntu 20 ).
The error message:
Die Installation aus einer nicht signierten Paketquelle ist nicht möglich
(in English: Installation from an unsignet package source is not possible )

From what I found is that is takes an GnuPG - Key that needs to imported in my keyring.
Question: how do I get this key (or where can it be found)?

XnviewMP could be installed and was working fine in Lubuntu 18 (version 19 I dont know).

do you have tried the TGZ?

On Kubuntu 20.10 is the same. Cannot be installed, it gives a message that the program cannot full fill the dependencies and then stops.

when you start xnview.sh, what do you have?

On Kubuntu 20.10 I have downloaded XnViewMP-linux-x64.deb and tried to install it with QApt Package Installer but when it starts it immediately stops and gives the ERROR massage as "Cannot satisfy dependencies".

When I tried to start from .../Downloads/XnView/opt/XnView/xnview.sh it ask whether to open, execute or cancel. If I choose Execute then the program starts. There should be a way to install so that I will have a a chance to start it normally from the Application Launcher, but not from Dolphin File Manager.

What could be the missing dependencies so I can be able to install them one by one.

I'm facing the same issues. Can't install xnview.
What are the command lines for the terminal input?
Cheers Jens

Go to the directory where you have the XnView installation file that exists. Then extract the file. The file creates another XnView folder and extracts it there. Open the folder then you will see another folder named " opt ". Open that folder then you will see a file name " xnview.sh " double click on that, a notification window will open asking to " open, execute or cancel ". Click on " execute " then wait for a second. There you will have XnView program will start.
If you cannot install it normally then you have to start it in this way.
There is one thing that I do not understand is. If it works like this why it says " cannot satisfy the necessary dependencies ". If it is not satisfying the necessary dependencies then some parts of XnView are not working normally, it should be working with some features missing which I did not recognize. If it works normally without missing any features then it should have been installed normally.
The is something missing but I do not understand. Maybe that will be corrected by the XnView team. Hoping for that and waiting with my fingers crossed.

Thanks for your reply.
I copied the XnViewMP-linux-x64.tgz from here https://www.xnview.com/de/xnviewmp/
unpacked in the dowload folder but there wasn't a "opt" directory
see attached screenshot
a double click on xnview.sh opened the text editor
no "open, execute or cancel" request

But anyhow: I just tried again a doubleclick on XnViewMP-linux-x64.deb and all of a sudden it started!
Don't ask why.
Thanks anyway! Cheers Jens

By clicking on the xnview.sh the program starts. While installing from the original installation file it gives a message that there are missing things by saying "Cannot satisfy the dependencies". What I understand from this message is: There are some missing dependencies so the program will not be working fully. So what is missing? That is what I wanted to understand so we can be able to comply the needed dependencies so the program will work fully.

Yes found a solution in French language and followed the order of the commands and it is solved.
So you can be able to follow the same:
sudo apt-get update
sudo apt-get install libopenal1
sudo apt-get install libxcb-xinerama0
sudo dpkg -i XnViewMP-linux-x64.deb

Just follow the 4 lines after each other and is solved.

Just before giving the last command you have to know in which directory you downloaded your file " XnViewMP-linux-x64.deb ".
sudo dpkg -i XnViewMP-linux-x64.deb or something like below
sudo dpkg -i /home downloads/XnView/Latest Version/XnViewMP-linux-x64.deb

I always install xnview packages directly using apt-get with command line apt-get install /path/to/package.deb or apt-get install ./package.deb as it always installs all the dependencies when needed. For xnview it can be /path/to/XnViewMP-linux-x64.deb or ./XnViewMP-linux-x64.deb as parameter for apt, both works, not forgetting ./ for relative path names. Actual numbers replaced with hashtag (#) where applicable.

thanks @ juozas
I had the same problem of dependencies (as I used first the .deb installer) with version 1.3.1 on Kubuntu 22.4
But with The dependencies had been automaticaly installed too