After updating from Ubuntu 18.04 to 20.04 z-push no longer works

[zwockel]

content of z-push-error.log:
[lars.becker] /usr/share/z-push/vendor/composer/ClassLoader.php:444 include(/usr/share/z-push/vendor/composer/…/…/backend/kopano/kopano.php): failed to open stream: No such file or directory (2)
28/12/2020 18:07:45 [ 3790] [WARN] [lars.becker] /usr/share/z-push/vendor/composer/ClassLoader.php:444 include(): Failed opening ‘/usr/share/z-push/vendor/composer/…/…/backend/kopano/kopano.php’ for inclusion (include_path=’:/usr/shar>
28/12/2020 18:07:45 [ 3790] [FATAL] [lars.becker] Fatal error: /usr/share/z-push/backend/combined/combined.php:576 - Declaration of BackendCombined::GetGALSearchResults($searchquery, $searchrange) must be compatible with ISearchProvider>
<ovider::GetGALSearchResults($searchquery, $searchrange, $searchpicture) (64)

Does anyone have a solution?

[tiredofit]

@zwockel What version of Z-Push are you using and how did you install it originally?