"Inkscape has received additional data from the script executed." error returned after saving the project as PDF, and after closing the window from the PDF viewer

[David]

I have just installed Inkscape 0.92.2 from this PPA:
https://code.launchpad.net/~inkscape.dev/+archive/ubuntu/stable
and I have encountered
a fairly known bug that used to occur in the 0.91 versions.
The problem appears when:

1) In a Terminal window, type: inkscape
2) Draw a line
3) copy the object
3) Open a File/New Inkscape
4) Copy-paste the object into the new project
5) File/Save As PDF (Use document's page size): trial.pdf
6) Open another terminal window
7) open the PDF with any PDF visualizer through that terminal, i.e
okular trial.pdf or evince trial.pdf
8) Close the pdf file.

The error message displayed in the Inkscape interface is the following:

"""
Inkscape has received additional data from the script executed. The script did not return an error, but this may indicate the results will not be as expected.

You need to install the UniConvertor software.
For GNU/Linux: install the package python-uniconvertor.
For Windows: download it from
https://sk1project.net/modules.php?name=Products&product=uniconvertor&op=download
and install into your Inkscape's Python location
"""
Inkscape enters into a loop of messages and the system is automatically logged out so that you loose everything.

I have re-installed via:

sudo apt-get remove inkscape
sudo apt-get remove --auto-remove inkscape
sudo apt-get purge inkscape
sudo apt-get purge --auto-remove inkscape

sudo add-apt-repository ppa:inkscape.dev/stable
sudo apt-get update
sudo apt-get install inkscape

but the problem persists.

I am running Ubuntu 14.04.5 LTS

This unables to use Inkspace properly, since it crashes unexpectedly.
Is there a way of fixing this?

[David (davidcb)]

With the newer version of Inkscape 0.92.3, I can also reproduce the same bug following steps 1) to 8).

[David (davidcb)]

Please see attached video (inkscape-3.ogv) in the previous comment. In that video I monitor all steps

[David (davidcb)]

When clicking "OK" several times, in the end the whole system crashes and you are looged out loosing all the information.