As suggested before I can agree with the solution of turning off the pagebreak plugin and it will stay turned off in the case of updates too. But if you do not want to use that solution, then:
maybe you would like this solution a little more with which you can delete that Exception thrown in pagebreak.php file, with an override of that file. Many people, even in Joomla extension developers community, do not know that there are relatively easy ways to override, not only template/layout files, but Model, Controller and View files too in Joomla. So that way you could just 'delete' that unneeded Exception object.
The full write-up of how to override Joomla components' views, models, controllers is here: https://docs.joomla.org/How_to_override_the_component_mvc_from_the_Joomla!_core
Hope this can help you.
(I have not checked this override method on plugins though, but according to the override helper plugin developer, it works on plugins' classes too).