NullPointerException (AsyncSocketServlet:54 < ...)

Does anyone know what could cause a /api/socket - NullPointerException (AsyncSocketServlet:54 < ...) error?
I use Teltonika devices and get the error quite frequently but cannot really see any issues when looking at devices in the web app.

I think the error indicates that you don't have a session.

Thanks Anton, do you know what might be causing it?
It seems to appear in the log file every minute.

It means someone left web app and it keeps trying to reconnect every minute.

Hi, I'm seeing this too:

 WARN: /api/socket - Cannot invoke "java.lang.Long.longValue()" because the return value of "javax.servlet.http.HttpSession.getAttribute(String)" is null - NullPointerException (AsyncSocketServlet:54 < ...)

Is there a fix?
Thx.

Why do you need to fix it?

i'ts just a warning indeed, should we leave it as it is ?
with lots of mobile app users, wouldn't this fill the log?
Thx

It shouldn't happen more than once per session, so shouldn't be a problem.