when I create IOU with http://localhost:10015/web/example , the Exception throw

[sportscar]

open the browser and access the URL: http://localhost:10015/web/example,
Click the "Create IOU" button and choose a Counter-party, and given 10 for Value. and then click "Create IOU" button.
then a message popup:
"
java.io.NotSerializableException: net.corda.core.contracts.TransactionState -> data(net.corda.core.contracts.ContractState) -> Constructor parameter - "arg0" - doesn't refer to a property of "class com.example.state.IOUState" -> class com.example.state.IOUState
"
It's just popup when I run the demo in IntelliJ environment. but under the Terminal is working fine.
what's the point?

Thanks!