{"record":{"id":"ad861640a935ae1c","repo":"nats-io/nats-server","slug":"processleafmsgargs-bad-or-missing-reply-indicator","errorCode":null,"errorMessage":"processLeafMsgArgs Bad or Missing Reply Indicator: '%s'","messagePattern":"processLeafMsgArgs Bad or Missing Reply Indicator: '(.+?)'","errorType":"validation","errorClass":null,"httpStatus":null,"severity":"error","filePath":"server/leafnode.go","lineNumber":3269,"sourceCode":"\n\tc.pa.arg = arg\n\tswitch len(args) {\n\tcase 0, 1:\n\t\treturn fmt.Errorf(\"processLeafMsgArgs Parse Error: '%s'\", args)\n\tcase 2:\n\t\tc.pa.reply = nil\n\t\tc.pa.queues = nil\n\t\tc.pa.szb = args[1]\n\t\tc.pa.size = parseSize(args[1])\n\tcase 3:\n\t\tc.pa.reply = args[1]\n\t\tc.pa.queues = nil\n\t\tc.pa.szb = args[2]\n\t\tc.pa.size = parseSize(args[2])\n\tdefault:\n\t\t// args[1] is our reply indicator. Should be + or | normally.\n\t\tif len(args[1]) != 1 {\n\t\t\treturn fmt.Errorf(\"processLeafMsgArgs Bad or Missing Reply Indicator: '%s'\", args[1])\n\t\t}\n\t\tswitch args[1][0] {\n\t\tcase '+':\n\t\t\tc.pa.reply = args[2]\n\t\tcase '|':\n\t\t\tc.pa.reply = nil\n\t\tdefault:\n\t\t\treturn fmt.Errorf(\"processLeafMsgArgs Bad or Missing Reply Indicator: '%s'\", args[1])\n\t\t}\n\t\t// Grab size.\n\t\tc.pa.szb = args[len(args)-1]\n\t\tc.pa.size = parseSize(c.pa.szb)\n\n\t\t// Grab queue names.\n\t\tif c.pa.reply != nil {\n\t\t\tc.pa.queues = args[3 : len(args)-1]\n\t\t} else {\n\t\t\tc.pa.queues = args[2 : len(args)-1]","sourceCodeStart":3251,"sourceCodeEnd":3287,"githubUrl":"https://github.com/nats-io/nats-server/blob/3a66a489d262bf89b71a71c955c94920394532f3/server/leafnode.go#L3251-L3287","documentation":"Leaf-node protocol parse guard: in the long argument form the reply indicator token (args[1]) is not a single '+' or '|' character, so the reply/queue layout of the message is unrecognized.","triggerScenarios":"Thrown at server/leafnode.go:3269 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Ensure peers emit only '+' or '|' reply indicators","Check for version mismatch between leaf nodes","Inspect raw traffic for corruption"],"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"}