I need still an answer. Also other users have the same issue (see comment from user SJW): https://wordpress.org/support/topic/php-fatal-error-uncaught-error-class-name-must-be-a-valid-object-or-a-string/
Still no answer and no solution…..
It is a great pity that you do not provide support here. We would even be willing to pay for a working solution.