can't reach Website after Session Reset

Hi everybody,

i might need your help
when i'm in running server, sometimes after a few hours and every time after session reset (via tools), i simply can't reach the website anymore.
i'm trying from browser via localhost:8888/$/start

i know it's some setting in my program, because in a new, simple "Hello World" it works perfectly fine.

Does anyone of you have an idea, what could cause this issue?
Sorry if that's a little general asked, but i don't have any idea what could cause it.

if you need further infos, please just ask.
the used Version of IntraWeb is 15.5.8 and it's running on C++ Builder 10.3

Greetings,
 Bjoern