# MQTT - Downlinks

**URL:** <https://www.thethingsnetwork.org/forum/t/mqtt-downlinks/44004>\
**Category:** V3 Integrations\
**Created:** [February 9, 2021, 3:30am UTC](https://www.thethingsnetwork.org/forum/t/mqtt-downlinks/44004 "2021-02-09T03:30:37Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![PleaseRain](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/pleaserain/32/35697_2.png) [@PleaseRain](https://www.thethingsnetwork.org/forum/u/PleaseRain)\
**Post date:** [February 9, 2021, 3:30am UTC](https://www.thethingsnetwork.org/forum/t/mqtt-downlinks/44004/1 "2021-02-09T03:30:38Z")

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Having migrated my application and devices to V3. My MQTT downlinks which were working on V3 have stopped working and return  
“v3/water-tank-monitoring@ttn/devices/water-tank-node/down/failed”  
When I look on the V3 console:  
 ![image](https://www.thethingsnetwork.org/forum/uploads/default/original/3X/a/2/a25a9c75eadc6d8cc76d84a2dc0d7aa9e99dc6a4.png)  
The downlink message has been received OK with the payload intact, but is dropped because of an “Unknown session” error  
“data”: {  
“@type”: “[type.googleapis.com/ttn.lorawan.v3.ErrorDetails](http://type.googleapis.com/ttn.lorawan.v3.ErrorDetails)”,  
“namespace”: “pkg/networkserver”,  
“name”: “unknown\_session”,  
“message\_format”: “unknown session”,  
“correlation\_id”: “1b14362dff7d4f54a8d093a87a9d0764”,  
“code”: 5

Any ideas?

Edit: I solved the problem by creating a new application and migrating the devices. It works fine now.

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<div class="post-metadata">

**Author:** ![vaasseniot](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/vaasseniot/32/45150_2.png) [@vaasseniot](https://www.thethingsnetwork.org/forum/u/vaasseniot)\
**Post date:** [February 9, 2021, 6:45am UTC](https://www.thethingsnetwork.org/forum/t/mqtt-downlinks/44004/2 "2021-02-09T06:45:23Z")

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I did get the exact same error message yesterday as wel, not by scheduling a downlink by MQTT but within the console.