# JSON Payload not getting updated in MQTT Engine folder on publishing second time

**URL:** <https://forum.inductiveautomation.com/t/json-payload-not-getting-updated-in-mqtt-engine-folder-on-publishing-second-time/108703>\
**Category:** Ignition\
**Tags:** perspective\
**Created:** [July 21, 2025, 5:19am UTC](https://forum.inductiveautomation.com/t/json-payload-not-getting-updated-in-mqtt-engine-folder-on-publishing-second-time/108703 "2025-07-21T05:19:49Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Samkcr](https://avatars.discourse-cdn.com/v4/letter/s/7c8e57/32.png) [@Samkcr](https://forum.inductiveautomation.com/u/Samkcr)\
**Post date:** [July 21, 2025, 5:19am UTC](https://forum.inductiveautomation.com/t/json-payload-not-getting-updated-in-mqtt-engine-folder-on-publishing-second-time/108703/1 "2025-07-21T05:19:49Z")

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Hi,  
I am getting JSON payload from MES system on a specific topic and it is received in MQTT Engine as tag value. This is working fine. But when we publish second time from MES the value not getting updated in MQTT Engine. Not sure what causing this issue.  
Example Topic : Enterprise/Site/Line/Machine1 and the same I have subscribed in the Custom Name space. Also where I can check the Queue of the received messages?

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<div class="post-metadata">

**Author:** ![fakcior](https://avatars.discourse-cdn.com/v4/letter/f/ee59a6/32.png) [@fakcior](https://forum.inductiveautomation.com/u/fakcior)\
**Post date:** [July 21, 2025, 9:51am UTC](https://forum.inductiveautomation.com/t/json-payload-not-getting-updated-in-mqtt-engine-folder-on-publishing-second-time/108703/2 "2025-07-21T09:51:52Z")

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Hard to say without additional information, but keep in mind this: if payload received is exactly the same as previously received one, the MQTT Engine tag timestamp will not be updated.  
Have you tried investigating Gateway log?

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<div class="post-metadata">

**Author:** ![tgarrison](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/tgarrison/32/80965_2.png) [@tgarrison](https://forum.inductiveautomation.com/u/tgarrison)\
**Post date:** [July 21, 2025, 12:32pm UTC](https://forum.inductiveautomation.com/t/json-payload-not-getting-updated-in-mqtt-engine-folder-on-publishing-second-time/108703/3 "2025-07-21T12:32:17Z")

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You can use something like MQTT-Explorer to watch the data flowing in the Broker, and also to test publish data. May give you a hand troubleshooting.

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<div class="post-metadata">

**Author:** ![Samkcr](https://avatars.discourse-cdn.com/v4/letter/s/7c8e57/32.png) [@Samkcr](https://forum.inductiveautomation.com/u/Samkcr)\
**Post date:** [July 22, 2025, 7:22am UTC](https://forum.inductiveautomation.com/t/json-payload-not-getting-updated-in-mqtt-engine-folder-on-publishing-second-time/108703/4 "2025-07-22T07:22:06Z")

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Hi,  
Error message received in the log and while publishing I am changing the data

StringPayloadHandler 22Jul2025 12:33:30 Invalid tag at path 'Test/Line/MachineData' - unable to handle payload on custom namespace topic=Line/MachineData

Refer the attachment on custom namespace setting which I have set now

I have also enabled the option parse the JSON Payload it is working...  
So my question is when we get the JSON payload it is mandatory to enable the parsing?

 ![Subscribe](https://us1.discourse-cdn.com/inductiveautomation/original/3X/4/5/451119b910ad46e9d41095a9de62b3d3a5304488.png)

payload {  
"DateTime": "",  
"Partnumber": "",  
"Worknumber": "",  
"Serialnumber": "",  
"Workcenter": "",  
"ParentWorkcenter": "",  
"QualityStatus": ""  
"ErrorCode": "",  
"Quantity":""  
}

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<div class="post-metadata">

**Author:** ![fakcior](https://avatars.discourse-cdn.com/v4/letter/f/ee59a6/32.png) [@fakcior](https://forum.inductiveautomation.com/u/fakcior)\
**Post date:** [July 22, 2025, 7:43am UTC](https://forum.inductiveautomation.com/t/json-payload-not-getting-updated-in-mqtt-engine-folder-on-publishing-second-time/108703/5 "2025-07-22T07:43:06Z")

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There is missing comma after QualityStatus field.

It is not mandatory to enable JSON parsing for such payloads.

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<div class="post-metadata">

**Author:** ![Samkcr](https://avatars.discourse-cdn.com/v4/letter/s/7c8e57/32.png) [@Samkcr](https://forum.inductiveautomation.com/u/Samkcr)\
**Post date:** [July 22, 2025, 5:06pm UTC](https://forum.inductiveautomation.com/t/json-payload-not-getting-updated-in-mqtt-engine-folder-on-publishing-second-time/108703/6 "2025-07-22T17:06:12Z")

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Hi,  
While copy paste here I missed that... But that was not the issue... It is not working without parse  
only with parse I am getting the payloads correctly on each tags