Olga, thanks for promt reply
But I’m using WPBakery theme and don’t have any options they are discussing. So I’ve just checked memory settings – there is 512 Mb allocated to server, when theme requires only 128 Mb.
Anyway, I’ve found solution in different topic, so I’ll leave it here in case somebody experiences same issue:
you need to add
<Location "/">
SubstituteMaxLineLength 20m
</Location>
in the end of htaccess.conf file, located in /wordpress/conf directory
Thank you for help, Olga!
Have a nice day!