RAK3172 MIC mismatch

After resetting to defaults and going step by step as described still the error “MIC mismatch” comes up.

I used this documentation to set things up: RAK3172 Module Quick Start Guide | RAKwireless Documentation Center

See the commands and values I typed in.

Here you can see the packet that arrived at the gateway (RAK7268).

(see screenshot above)

Here you can see what the TTN log says.

(see screenshot above)

Here you can see what the packet decoder tells us.


(see screenshot above)

To me it looks like the MIC is wrong as calculated by the module.

Is there a firmware update under way? What can I do about this? Thank you.

p.s. I have also a MIC mismatch when using the network server functionality of the RAK7268. So it does not seem to be an issue with TTN.

MIC mismatch error is usually caused by the APPKEY.

I suggest you try to generate a new APPKEY and use that on your RAK3172. You can generate a new one under Join Settings in the General Settings tab of your TTN device console

Another thing you can do is to reset the device using ATZ command after setting the EUIs/KEY and before joining the network.

I went through the process many times without success.

BUT to reboot the module with ATZ did SOLVE it.

So these were the steps…


There seems to be that bug that joining is possible only after rebooting the module after setting the APPKEY. That’s somehow annoying but NEVERTHELESS it WORKS that way! I could not find any hint on that in the documentation. Thank you for the advice. I assume this will be the cause of many problems or seemingly erratic behaviour.

Have a nice weekend. Cheers.

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Good thing it works. We have new RAK3172 FW that is based on RUI3. I never experience this issue anymore. I suggest you update your firmware and see if things will improve.

There are minor differences on the old RAK3172 FW and the RUI3 though.

Thank you. We can close.

Sorry. One last thing… where is the newest firmware supposed to be?

I only found RAKwireless Downloads

And there it seems to be RAK3172_v1.0.4_App_20220218.bin - i.e. version 1.0.4.

But here (RAK3172 Module AT Command Manual | RAKwireless Documentation Center) it says that 1.0.4 was deprecated.

Could you please clarify. Thank you.

Hi @tb4450 ,

Please follow this DFU guide. The links are updated and will send you to the right links.

The updated RAK3172 FW is now based on RUI3.

RUI3 is a firmware platform we created so we can unify the firmware of our devices regardless of chipsets. Also, it allows you to compile firmware directly on the device and not relying on the AT commands and external host MCU.

Thank you. All went fine. I could upgrade and test OK.

What you mention about RUI3 that allows to compile firmware directly is very interesting. I will have a look.

Finally, we are done here. Thanks.