# MIC Mismatch when adding device to app

**URL:** <https://www.thethingsnetwork.org/forum/t/mic-mismatch-when-adding-device-to-app/43419>\
**Category:** The Things Stack v3\
**Created:** [January 28, 2021, 4:16pm UTC](https://www.thethingsnetwork.org/forum/t/mic-mismatch-when-adding-device-to-app/43419 "2021-01-28T16:16:28Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![david\_graham](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/david_graham/32/35697_2.png) [@david\_graham](https://www.thethingsnetwork.org/forum/u/david_graham)\
**Post date:** [January 28, 2021, 4:16pm UTC](https://www.thethingsnetwork.org/forum/t/mic-mismatch-when-adding-device-to-app/43419/1 "2021-01-28T16:16:29Z")

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Started migrating my devices over to TTN Stack V3 and hit an issue with my first device! Admittedly this is a new device so not had it running on V2 before.

In my Application I can see a JOIN REQUEST coming in and then being sent back out, promptly followed by a MIC Mismatch error and the JOIN REQUEST is then dropped.

I have double checked all DEVICE & JOIN EUI’s but still getting the same error, can anyone point me in the right direction?

![image](https://www.thethingsnetwork.org/forum/uploads/default/original/3X/7/1/71424ff5181caedc73545de91a8a675cfbc0d0ca.png)

![image](https://www.thethingsnetwork.org/forum/uploads/default/original/3X/e/9/e9bbd5343a8f6f6a0ece6e6ca3a93fbac780ba7c.png)

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**Author:** ![cslorabox](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/cslorabox/32/35697_2.png) [@cslorabox](https://www.thethingsnetwork.org/forum/u/cslorabox)\
**Post date:** [January 28, 2021, 4:37pm UTC](https://www.thethingsnetwork.org/forum/t/mic-mismatch-when-adding-device-to-app/43419/2 "2021-01-28T16:37:15Z")

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Probably you have a mismatch in the EUI, the App Key, or the LoRaWAN version.

You can try decoding the raw uplink by some other means to prove it.

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**Author:** ![david\_graham](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/david_graham/32/35697_2.png) [@david\_graham](https://www.thethingsnetwork.org/forum/u/david_graham)\
**Post date:** [January 29, 2021, 9:27am UTC](https://www.thethingsnetwork.org/forum/t/mic-mismatch-when-adding-device-to-app/43419/3 "2021-01-29T09:27:28Z")

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All sorted now, thanks. Browan had issued an incorrect App key, new key issued and join went through OK.

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**Author:** ![htdvisser](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/htdvisser/32/45312_2.png) [@htdvisser](https://www.thethingsnetwork.org/forum/u/htdvisser)\
**Post date:** [January 29, 2021, 4:08pm UTC](https://www.thethingsnetwork.org/forum/t/mic-mismatch-when-adding-device-to-app/43419/4 "2021-01-29T16:08:38Z")

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