{"record":{"id":"d6e8e9ad6161e956","repo":"nats-io/nats-server","slug":"unknown-trace-type-v","errorCode":null,"errorMessage":"unknown trace type %v","messagePattern":"unknown trace type (.+?)","errorType":"validation","errorClass":null,"httpStatus":null,"severity":"error","filePath":"server/msgtrace.go","lineNumber":175,"sourceCode":"\tMsgTraceJetStreamType:      MsgTraceJetStream{},\n\tMsgTraceEgressType:         MsgTraceEgress{},\n}\n\nfunc (t *MsgTraceEvents) UnmarshalJSON(data []byte) error {\n\tvar raw []json.RawMessage\n\terr := json.Unmarshal(data, &raw)\n\tif err != nil {\n\t\treturn err\n\t}\n\t*t = make(MsgTraceEvents, len(raw))\n\tvar tt MsgTraceBase\n\tfor i, r := range raw {\n\t\tif err = json.Unmarshal(r, &tt); err != nil {\n\t\t\treturn err\n\t\t}\n\t\ttr, ok := msgTraceInterfaces[tt.Type]\n\t\tif !ok {\n\t\t\treturn fmt.Errorf(\"unknown trace type %v\", tt.Type)\n\t\t}\n\t\tte := tr.new()\n\t\tif err := json.Unmarshal(r, te); err != nil {\n\t\t\treturn err\n\t\t}\n\t\t(*t)[i] = te\n\t}\n\treturn nil\n}\n\nfunc getTraceAs[T MsgTrace](e any) *T {\n\tv, ok := e.(*T)\n\tif ok {\n\t\treturn v\n\t}\n\treturn nil\n}\n","sourceCodeStart":157,"sourceCodeEnd":193,"githubUrl":"https://github.com/nats-io/nats-server/blob/3a66a489d262bf89b71a71c955c94920394532f3/server/msgtrace.go#L157-L193","documentation":"Raised in MsgTraceEvents.UnmarshalJSON: a trace event's \"type\" field does not map to any entry in the msgTraceInterfaces registry (MsgTraceJetStreamType, MsgTraceEgressType, etc.), so the decoder cannot pick a concrete trace type to unmarshal into. Typically means the JSON was produced by a newer/older server with unknown trace types.","triggerScenarios":"Thrown at server/msgtrace.go:175 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Ensure the producer and consumer of the trace JSON run compatible server versions","Ignore/skip unknown trace types if forward compatibility is required"],"exampleFix":null,"handlingStrategy":"validation","validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"3a66a489d262bf89b71a71c955c94920394532f3","analyzedAt":"2026-09-02T04:41:54.247Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-08T10:18:20.063Z"}