Error: No data

I was doing volume testing and noticed the following log entry that I have never seen before:
…
Error: No data: /ocall/callstartwrapper?line=1&vxstate=end
VxInterpClientThread stop
…
Please advise as to what is causing those bolded lines?

This is called when a call is disconnected (vxstate=end) so the app has a chance to clean up the session data. You can safely ignore the message, which is from some library functions. It simply says the call does not return any info.