I'm running Inkscape 0.92 on Debian GNU/Linux 9.8 (stretch).
When I try to "copy" an object in Inkscape I get an error about UniConvertor not beeing installed.
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
I get the following windows displayed as a result of the error in the given order: