If you are using ETS-OTA solution to test A-GPS, for some exceptions that ETS software stopped to run test case, then you will have error as the below picture:
Solution
Step 1, you should exit OTA application server from windows taskbar first.
Steo 2, restart OTA applicaction server from Desktop or the installation folder.
Now, you are ok to run ETS-OTA again with Spirent plug-in