Error getting Response; null
It appears that if the action of running a call would clear out the response and release the used memory that SoapUI might function as excepted. I can close the app and reopen it to get the call to work again so this seems reasonable. Another option could be to allow the response to be removed by the user.
[Solved] I was getting the message "error getting response; null".
I added the files "wss4j-1.6.18.jar" and "xmlsec-1.5.8.jar" as shown below in SoapUI 5.4.0. so i solved my problem about that message. You can get the lib files "wss4j-1.6.18.jar" and "xmlsec-1.5.8.jar" from ReadyAPI 2.6.0 that you downloaded .