When the Ivr Engine tries to evaluate a YourSite Explorer Device such as a Queue, Extension, or Variable and it can not be found.
Critical
If a caller reaches the part of the callflow that is referencing the missing device, the action will not be successful.
Check YourSite Explorer to ensure that the device has not been deleted.
To fix this issue there are 2 possible solution remove the device from the callflow or add the device and modify the activity to select the new added device.
CCM/IVR 6.0