9.04.17 php7.3 ajax-problem

Hello,
I tried Version 9.4.17 with php7.3 and nearly everything works in my project, except the following error occurring in 4 apps. I can not make out, what is wrong. There are no Ajax-events I wrote. Anyone any clue?

Help would be appreciated. Especially because going back to php7.0 leads to a non-opening SC9-lockin-page…

2 = count(): Parameter must be an array or an object that implements Countable
/var/www/vhosts/hoknet.de/scriptcase/sc9/devel/generator/nm_gp_ajax_init.php 13

reason found: in the advanced filter there were rules to store the filter criteria f?r the usr_login. Whenever there is a rule, the error occurs. So for now I have disabled rules and it translates. But in perspective rules would be fine…