Calling BP process from outside results in SOAP Fault : Couldn't create session - UNAVAILABLE

[sathishmark]

Hi, I'm getting the error in the subject when accessing an exposed Blueprism process from external tools. Enclosed screenshot shows the error received in postman. When I run the process in debug mode in BP client, it runs flawlessly. Can someone please point to what the problem could be. The error happens only for some processes in blueprism, not all. Some processes are also successful. Thanks Sathish 

[John__Carter]

Is the target machine running as a resource PC and is it idle when the call is made?