Created attachment 345 [details] Minimal model, that reproduces the exception I am running the uppaal64-4.1.20-stratego-8-beta3. I am using asserts in my functions as there are branches in the functions that such never be taken. When I am using the simulator and whenever a branch with an assert is possible, a JSON exception is called. It took me a while to figure out that it happened when an assert was hit. I have attached a minimal example that reproduced the error as soon as one starts the simulator. The exception text is `Expected field name "src", got "path"`. The stack trace from the command line: Expected field name "src", got "path" at com.uppaal.engine.protocol.JsonMessageParser.expectFieldName(JsonMessageParser.java:331) at com.uppaal.engine.protocol.JsonMessageParser.visitObjectField(JsonMessageParser.java:122) at com.uppaal.engine.protocol.viewmodel.SuccessorViewModel.accept(SuccessorViewModel.java:16) at com.uppaal.engine.protocol.JsonMessageParser.visitObject(JsonMessageParser.java:139) at com.uppaal.engine.protocol.JsonMessageParser.visitObject(JsonMessageParser.java:152) at com.uppaal.engine.protocol.JsonMessageParser.getGenericValue(JsonMessageParser.java:208) at com.uppaal.engine.protocol.JsonMessageParser.visitArray(JsonMessageParser.java:176) at com.uppaal.engine.protocol.JsonMessageParser.visitArrayField(JsonMessageParser.java:163) at com.uppaal.engine.protocol.viewmodel.SuccessorListViewModel.accept(SuccessorListViewModel.java:20) at com.uppaal.engine.protocol.JsonMessageParser.visitObject(JsonMessageParser.java:139) at com.uppaal.engine.protocol.JsonMessageParser.visitObjectField(JsonMessageParser.java:130) at com.uppaal.engine.protocol.viewmodel.GenericResponse.accept(GenericResponse.java:27) at com.uppaal.engine.protocol.JsonMessageParser.visitObject(JsonMessageParser.java:139) at com.uppaal.engine.protocol.JsonProtocol.getGenericResponse(JsonProtocol.java:432) at com.uppaal.engine.protocol.JsonProtocol.getTransitions(JsonProtocol.java:105) at com.uppaal.engine.EngineStub.getTransitions(EngineStub.java:687) at com.uppaal.engine.Engine.getTransitions(Engine.java:290) at on.gU.run(Unknown Source)
I confirm. Thanks for the report.