Error when managing displays from xibo backend

[stefan.meise]

Hi Forum,

our Xibo is a custom 3.0.8 installation on Ubuntu 20.
We have set up some displays (webOS and Windows) and these are each running the latest client. We would like to manage these displays from the backend and take screenshots of the display for example. When we open the list box for the display in the backend and select “Manage” or “Request Screen Shot”, we get the error message:

Argument 1 passed to Carbon\CarbonInterval::setLocalTranslator() must implement interface Symfony\Component\Translation\TranslatorInterface, instance of Carbon\Translator given, called in /srv/xibo-cms/vendor/nesbot/carbon/src/Carbon/Traits/Difference.php on line 835

(Please also have a look at the screenshots).
Does anyone have an idea where we can start? The setup seems to be ok otherwise.

Many thanks to you in advance!

[stefan.meise]

Solution found!
The problem was caused by an unclean upgrade from xibo 2 to 3.
After copying the vendor/symfony directory again, the error was fixed.