{"record":{"id":"2d9a2a7be9106752","repo":"nats-io/nats-server","slug":"js-api-timeout-must-be-a-positive-value","errorCode":null,"errorMessage":"JS API timeout must be a positive value","messagePattern":"JS API timeout must be a positive value","errorType":"validation","errorClass":null,"httpStatus":null,"severity":"error","filePath":"server/mqtt.go","lineNumber":233,"sourceCode":"var (\n\tmqttPingResponse     = []byte{mqttPacketPingResp, 0x0}\n\tmqttProtoName        = []byte(\"MQTT\")\n\tmqttOldProtoName     = []byte(\"MQIsdp\")\n\tmqttSessJailDur      = mqttSessFlappingJailDur\n\tmqttFlapCleanItvl    = mqttSessFlappingCleanupInterval\n\tmqttRetainedCacheTTL = mqttDefaultRetainedCacheTTL\n)\n\nvar (\n\terrMQTTNotWebsocketPort           = errors.New(\"MQTT clients over websocket must connect to the Websocket port, not the MQTT port\")\n\terrMQTTTopicFilterCannotBeEmpty   = errors.New(\"topic filter cannot be empty\")\n\terrMQTTMalformedVarInt            = errors.New(\"malformed variable int\")\n\terrMQTTSecondConnectPacket        = errors.New(\"received a second CONNECT packet\")\n\terrMQTTServerNameMustBeSet        = errors.New(\"mqtt requires server name to be explicitly set\")\n\terrMQTTUserMixWithUsersNKeys      = errors.New(\"mqtt authentication username not compatible with presence of users/nkeys\")\n\terrMQTTTokenMixWIthUsersNKeys     = errors.New(\"mqtt authentication token not compatible with presence of users/nkeys\")\n\terrMQTTAckWaitMustBePositive      = errors.New(\"ack wait must be a positive value\")\n\terrMQTTJSAPITimeoutMustBePositive = errors.New(\"JS API timeout must be a positive value\")\n\terrMQTTStandaloneNeedsJetStream   = errors.New(\"mqtt requires JetStream to be enabled if running in standalone mode\")\n\terrMQTTConnFlagReserved           = errors.New(\"connect flags reserved bit not set to 0\")\n\terrMQTTWillAndRetainFlag          = errors.New(\"if Will flag is set to 0, Will Retain flag must be 0 too\")\n\terrMQTTPasswordFlagAndNoUser      = errors.New(\"password flag set but username flag is not\")\n\terrMQTTCIDEmptyNeedsCleanFlag     = errors.New(\"when client ID is empty, clean session flag must be set to 1\")\n\terrMQTTEmptyWillTopic             = errors.New(\"empty Will topic not allowed\")\n\terrMQTTEmptyUsername              = errors.New(\"empty user name not allowed\")\n\terrMQTTTopicIsEmpty               = errors.New(\"topic cannot be empty\")\n\terrMQTTPacketIdentifierIsZero     = errors.New(\"packet identifier cannot be 0\")\n\terrMQTTUnsupportedCharacters      = errors.New(\"character not supported for MQTT topics\")\n\terrMQTTInvalidSession             = errors.New(\"invalid MQTT session\")\n\terrMQTTInvalidRetainFlags         = errors.New(\"invalid retained message flags\")\n\terrMQTTInvalidRetainedMessage     = errors.New(\"invalid retained message\")\n\terrMQTTSessionCollision           = errors.New(\"stored session does not match client ID\")\n\terrMQTTInvalidPublishLength       = errors.New(\"invalid publish message, variable header exceeds remaining length\")\n\terrMQTTAckPipelineStopped         = errors.New(\"QoS1 PUBACK pipeline has shut down while admitting a message, \" +\n\t\t\"abandoning the wait for its JetStream ack; failing the connection, \" +\n\t\t\"the client will re-send unacknowledged PUBLISH packets on reconnect\")","sourceCodeStart":215,"sourceCodeEnd":251,"githubUrl":"https://github.com/nats-io/nats-server/blob/3a66a489d262bf89b71a71c955c94920394532f3/server/mqtt.go#L215-L251","documentation":"Options.MQTT.JSAPITimeout bounds how long the server waits for JetStream API responses (publish/consumer requests) while serving MQTT clients. Negative durations fail option validation at server/mqtt.go:728 before startup. Zero is accepted and falls back to the default timeout.","triggerScenarios":"Assigning opts.MQTT.JSAPITimeout a negative duration such as -10*time.Second and starting the server; the same validation block as AckWait in ProcessOptions.","commonSituations":"Same class of mistakes as AckWait: sign typos in literals, arithmetic on clocks yielding negative durations, or misreading '-1 as default' conventions from other frameworks.","solutions":["Set MQTT.JSAPITimeout to a positive duration (e.g. 5*time.Second) or zero for the default.","Clamp dynamic computations before passing Options to NewServer.","Review config files for negative duration strings and correct them."],"exampleFix":"// before\nmo.JSAPITimeout = -10 * time.Second\n// after\nmo.JSAPITimeout = 5 * time.Second","handlingStrategy":"validation","validationCode":"if mo.JSAPITimeout < 0 {\n    return fmt.Errorf(\"JSAPITimeout must be >= 0, got %v\", mo.JSAPITimeout)\n}","typeGuard":null,"tryCatchPattern":"if err := opts.Process(); err != nil {\n    if strings.Contains(err.Error(), \"JS API timeout must be\") {\n        opts.MQTT.JSAPITimeout = 0 // revert to default\n    }\n}","preventionTips":["Same habits as AckWait: positive literals or zero for defaults.","Guard dynamically computed timeouts with if d < 0 { d = 0 }.","Validate durations in config-file loading code before constructing Options."],"tags":["mqtt","config","validation","jetstream"],"backgroundTag":"invalid-enum-value","analyzedSha":"3a66a489d262bf89b71a71c955c94920394532f3","analyzedAt":"2026-09-02T04:41:54.247Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-08T10:18:20.063Z"}