What should I set in TRACE_PATH for Http sender?

Any Linux or Network path gives me an error in ifsapp-connect logs:

...IOException: Could not create directory or the file exists and is not a directory…

Documentation explain nothing 
 

TRACE_PATH
Defines the path where the trace logs (i.e. the request and response) of the sender will be created. If not specified there will be no trace logs created.

Any advice?