[otrs] html error 500 in otrs 2.4.5

Hi all, when i try to open a ticket with the body in HTML and the body is "big". There is an error http 500 after a few minutes. The size of the html body is 498 KB . Do you have any idea in how to solve it ? This error starts whit the version 2.4.1. and persists in 2.4.5 Thanks in advance