[SR-Users] Kamailio python_exec getting randomly TypeError

Dear Kamailio users, I am trying to use a python script using the module app_python3 to do some billing calculations. The only argument i want to pass to the python script is duration which i calculate in event_route[dialog:start] { $dlg_var('call_start') = $TS; event_route[dialog:end] { $var('v_duration') = $TS - $dlg_var('call_start'); So my $var('v_duration') has the duration of the call in seconds. Then i execute from my kamailio.cfg: python_exec("calculateCost","$var('v_duration')"); The script works randomly - sometimes all is good and sometimes it throw error : app_python3 [python_support.c:156]: python_handle_exception(): apy_exec: calculateCost(4): Unhandled exception in the Python code: TypeError: an integer is required (got type NoneType) The above exception was the direct cause of the following exception: Traceback (most recent call last): File "/etc/kamailio/kamailio-python.py", line 282, in calculateCost duration = int(duration) It looks like the kamailio log show calculateCost(4) so argument 4 is passed to python function but once it executes it appear like there is no string/integer but NoneType argument. I cannot figure this out why this randomly happens - maybe it's an app_python3 module issue? Looking to hear back from you! BR, Tom