# Weird delay output (empty message)

**URL:** <https://discourse.nodered.org/t/weird-delay-output-empty-message/99489>\
**Category:** General\
**Created:** [23 October 2025 08:49 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489 "2025-10-23T08:49:28Z")\
**Posts on this page:** 12\
**Page:** 1

<div class="post-metadata">

**Author:** ![ThingsTinkerer](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@ThingsTinkerer](https://discourse.nodered.org/u/ThingsTinkerer)\
**Post date:** [23 October 2025 08:49 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/1 "2025-10-23T08:49:28Z")

</div>

Got a weird error which I tracked down to delay node (configured as rate limit with delay). Not sure what is going on.

NR version: 4.1.1.  
Node: 22

When sending flush control message, it also outputs the control message from the delay (with flush prop removed).

The message I define with flush includes \_msgid and \_event properties. But I didn't set this in the function node it originated from. I used this function node to return flush message back to queue: `return { flush: 1 };`.

---

<div class="post-metadata">

**Author:** ![ThingsTinkerer](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@ThingsTinkerer](https://discourse.nodered.org/u/ThingsTinkerer)\
**Post date:** [23 October 2025 09:17 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/2 "2025-10-23T09:17:26Z")

</div>

Digged some more, and it seems to be affected by link in/out nodes. When function node use `return {reset: 1}`, it automagically adds \_msgid prop. When it goes through link node, \_event prop is added.

Seems like queue node can handle msg with reset, \_msgid and \_event. But when I try the same with flush, \_msgid and \_event, it treats it as both a flush control message and a new message. This removes the flush prop, but keeps \_msgid and \_event. Here is a simplified example:

 ![bilde](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/8/7/875af2a7f31420d9a246daf7140971f5e6bab51e.png)

```auto
[
    {
        "id": "afd7119ab90da785",
        "type": "inject",
        "z": "a7674a4aaf8a3c64",
        "name": "",
        "props": [],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "",
        "x": 1390,
        "y": 980,
        "wires": [
            [
                "bd046bd14e8ad79a"
            ]
        ]
    },
    {
        "id": "bd046bd14e8ad79a",
        "type": "function",
        "z": "a7674a4aaf8a3c64",
        "name": "flush",
        "func": "// reset any leftover in previous queue\nreturn { flush: 1 };",
        "outputs": 1,
        "timeout": "",
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 1510,
        "y": 980,
        "wires": [
            [
                "1a5fb9a9de620724",
                "9ae07de9afcd7ef9"
            ]
        ]
    },
    {
        "id": "afa13d8bc425b20b",
        "type": "link in",
        "z": "a7674a4aaf8a3c64",
        "name": "link in 10",
        "links": [
            "1a5fb9a9de620724"
        ],
        "x": 1855,
        "y": 980,
        "wires": [
            [
                "7cd67bbf79c1dcad",
                "59bf2547ebe2d557"
            ]
        ]
    },
    {
        "id": "1a5fb9a9de620724",
        "type": "link out",
        "z": "a7674a4aaf8a3c64",
        "name": "link out 6",
        "mode": "link",
        "links": [
            "afa13d8bc425b20b"
        ],
        "x": 1615,
        "y": 980,
        "wires": []
    },
    {
        "id": "9ae07de9afcd7ef9",
        "type": "debug",
        "z": "a7674a4aaf8a3c64",
        "name": "debug 1: _msgid added",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "true",
        "targetType": "full",
        "statusVal": "",
        "statusType": "auto",
        "x": 1710,
        "y": 1020,
        "wires": []
    },
    {
        "id": "7cd67bbf79c1dcad",
        "type": "delay",
        "z": "a7674a4aaf8a3c64",
        "name": "queue",
        "pauseType": "rate",
        "timeout": "5",
        "timeoutUnits": "seconds",
        "rate": "1",
        "nbRateUnits": "60",
        "rateUnits": "minute",
        "randomFirst": "1",
        "randomLast": "5",
        "randomUnits": "seconds",
        "drop": false,
        "allowrate": false,
        "outputs": 1,
        "x": 2110,
        "y": 980,
        "wires": [
            [
                "8ddc534d989cc697"
            ]
        ]
    },
    {
        "id": "59bf2547ebe2d557",
        "type": "debug",
        "z": "a7674a4aaf8a3c64",
        "name": "debug 2: _evemt added",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "true",
        "targetType": "full",
        "statusVal": "",
        "statusType": "auto",
        "x": 2030,
        "y": 1020,
        "wires": []
    },
    {
        "id": "91a80240032f6b46",
        "type": "inject",
        "z": "a7674a4aaf8a3c64",
        "name": "",
        "props": [],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "",
        "x": 1390,
        "y": 1080,
        "wires": [
            [
                "1729cb0bc398109f"
            ]
        ]
    },
    {
        "id": "1729cb0bc398109f",
        "type": "function",
        "z": "a7674a4aaf8a3c64",
        "name": "flush",
        "func": "// reset any leftover in previous queue\nreturn { flush: 1 };",
        "outputs": 1,
        "timeout": "",
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 1510,
        "y": 1080,
        "wires": [
            [
                "ecbc8660ad045e8a",
                "97934838227f3705"
            ]
        ]
    },
    {
        "id": "ecbc8660ad045e8a",
        "type": "debug",
        "z": "a7674a4aaf8a3c64",
        "name": "debug 1: _msgid added",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "true",
        "targetType": "full",
        "statusVal": "",
        "statusType": "auto",
        "x": 1710,
        "y": 1120,
        "wires": []
    },
    {
        "id": "97934838227f3705",
        "type": "delay",
        "z": "a7674a4aaf8a3c64",
        "name": "queue",
        "pauseType": "rate",
        "timeout": "5",
        "timeoutUnits": "seconds",
        "rate": "1",
        "nbRateUnits": "60",
        "rateUnits": "minute",
        "randomFirst": "1",
        "randomLast": "5",
        "randomUnits": "seconds",
        "drop": false,
        "allowrate": false,
        "outputs": 1,
        "x": 2110,
        "y": 1080,
        "wires": [
            [
                "65c1572afd9a258f"
            ]
        ]
    },
    {
        "id": "65c1572afd9a258f",
        "type": "debug",
        "z": "a7674a4aaf8a3c64",
        "name": "queue output: none",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "true",
        "targetType": "full",
        "statusVal": "",
        "statusType": "auto",
        "x": 2270,
        "y": 1080,
        "wires": []
    },
    {
        "id": "8ddc534d989cc697",
        "type": "debug",
        "z": "a7674a4aaf8a3c64",
        "name": "queue output: ghost message",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "true",
        "targetType": "full",
        "statusVal": "",
        "statusType": "auto",
        "x": 2310,
        "y": 980,
        "wires": []
    }
]

```

Seems like queue node has a bug that treats control messages with \_event prop as both control message and a new message for the queue?

Temp fix for me is to always add function node before queue node with this code:

```auto
const isControlMessage = msg.flush != null || msg.reset != null;
const hasEvent = msg._event != null;
if (isControlMessage && hasEvent) {
  delete msg._event;
}
return msg;

```

---

<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [23 October 2025 16:25 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/3 "2025-10-23T16:25:46Z")

</div>

The flush message must be empty apart from the flush (and \_msgid). The best way is to use a function node in the flush path, containing just  
`return {flush:1}`  
or similar.

---

<div class="post-metadata">

**Author:** ![ThingsTinkerer](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@ThingsTinkerer](https://discourse.nodered.org/u/ThingsTinkerer)\
**Post date:** [23 October 2025 20:37 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/4 "2025-10-23T20:37:47Z")

</div>

Moving function node to the other side of the link (after link in) would work yeah. However then I need to stack multiple links there, one for flush, one for reset and so on. Right now all the flushes and resets are before the link out. Admittedly a bit of code duplication. But then I use the same function node for reset to reset multiple nodes (delay + join), so it can go both ways. Flush command must be empty, but reset doesn't need to be? It's a very easy trap to go into, when you don't know all places that add meta data to your messages.

---

<div class="post-metadata">

**Author:** ![ThingsTinkerer](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@ThingsTinkerer](https://discourse.nodered.org/u/ThingsTinkerer)\
**Post date:** [30 October 2025 14:36 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/5 "2025-10-30T14:36:46Z")

</div>

I used to consider normal links as equivalent to "hidden" link in/out nodes. But to my surprise they are not interchangeable. For me, this was confusing as it caused a flow to crash. At least now I know and will take great care in future when dealing with link in/out nodes.

Perhaps too late now, but Node Red could benefit from separating msg into 2 parts: msg (as normal) and meta for meta data? This is how Thingsboard does it in their Rulechains. It's similar to Node Red, but in many other aspects much inferior.

---

<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [30 October 2025 16:03 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/6 "2025-10-30T16:03:35Z")

</div>

> [@ThingsTinkerer](#):
>
> I used to consider normal links as equivalent to "hidden" link in/out nodes

What is a normal link?

---

<div class="post-metadata">

**Author:** ![ThingsTinkerer](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@ThingsTinkerer](https://discourse.nodered.org/u/ThingsTinkerer)\
**Post date:** [30 October 2025 17:07 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/7 "2025-10-30T17:07:58Z")

</div>

They are called wires? The lines or cables between nodes. Normally you start out with the visible ones. Later, I tried the more advanced hidden/invisble wires, they are dotted if you select an entry/exit node.

---

<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [30 October 2025 17:24 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/8 "2025-10-30T17:24:09Z")

</div>

So are you saying you are seeing a difference between a wire and a link out/link in pair?  
There is a difference with link call/return as it has to add the return meta data to the message, but I am not aware of anything similar with link out/in.

---

<div class="post-metadata">

**Author:** ![ThingsTinkerer](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@ThingsTinkerer](https://discourse.nodered.org/u/ThingsTinkerer)\
**Post date:** [30 October 2025 20:37 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/9 "2025-10-30T20:37:07Z")

</div>

I have documented it here...

---

<div class="post-metadata">

**Author:** ![jbudd](https://avatars.discourse-cdn.com/v4/letter/j/5f8ce5/32.png) [@jbudd](https://discourse.nodered.org/u/jbudd)\
**Post date:** [30 October 2025 22:18 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/10 "2025-10-30T22:18:21Z")

</div>

It does seem surprising that if you send a msg like this _with no payload_

```auto
{
"topic": "This is going on the queue", 
"flush": 3
}

```

Then the delay node (Not a queue node, which does exist but this isn't it) will flush three messages _as well as_ adding the flush message to the queue.

I can see it might be useful in some circumstances though.

---

<div class="post-metadata">

**Author:** ![ThingsTinkerer](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@ThingsTinkerer](https://discourse.nodered.org/u/ThingsTinkerer)\
**Post date:** [31 October 2025 08:28 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/11 "2025-10-31T08:28:04Z")

</div>

Sorry for confusing node name. At least you added the topic yourself.

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [29 January 2026 08:28 UTC](https://discourse.nodered.org/t/weird-delay-output-empty-message/99489/12 "2026-01-29T08:28:30Z")

</div>

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