Do you have debug logging enabled in the device?
yes. Those logs are with Debug logging turned on.
That error message is only displayed when debug logging is enabled.
Any other ideas to make this work?
Is the outlet not turning on or off?
No, it does not turn on or off via Hubitat
@karnik.abhijeet what is the hardware version of your outlet?
I only have 1 of these devices, which admittedly I don't use very much anymore. The Meross app shows that my device has:
Model number: mpd100
Firmware version: 2.1.7
Hardware version: 2.0.0
Your firmware version is a different format and much higher.
I'm late to the game on this but I just spent the last 2 days trying to get my mss120b working. It was receiving updates but I was getting the same error as you when I tried to control it.
I also have the msg100 garage door opener which requires a KEY in addition to all the other parameters. Anyway, I checked out the code for the msg100 and saw how it's signing the requests differently than the mss120b. I lifted the code from the 100 and put it in the 120b and it worked perfectly. Looks like there was a firmware update somewhere along the way that changed how requests need to be signed.
Thank you for the lead. I'll leave code lifting and placing to the experts. 
It would be nice to put those plug switches to work.
Hello, I am new here. This is my first post and Hubitat was just installed today,
Can someone help me understand how I can create the proper key for signing the payload? I am using a new switch model: mss510xr. The driver effectively works as the error received is a signing error. I am not new to coding and no concerns with updating the driver.
In looking at some related python code for Meross_IOT: MerossIot/manager.py at 0.4.X.X · albertogeniola/MerossIot · GitHub
The error seems to be related to the need for the Meross apps' userid and Password to properly generate the key (or retrieve token), to send the command. The messageID was easy enough to get using the Meross App and HTTP Catcher,
Any hints or pointers would be appreciated. I have several Meross switches and will gladly contribute the updates.
Thank you
You can find some great instructions here - look at the bottom of the page and it tells you exactly how to get the key: GitHub - ithinkdancan/hubitat-meross: Hubitat Drivers for Meross Smart Plugs
Got it. Thank you.
Is it worth putting this into a "Generate Key" method within the driver using email and password?
I ask as I was currently working on such. Perhaps it is already known why this should not be done.
Thank you
I made the unfortunate mistake to buy Meross devices on a special - never again and designated to the bin.
I am using the mini wi-fi driver for my meross switches. Some of them are power switches, model mss310. Any chance the driver can be changed to capture power readings?
all these types work with basic on/off
mss210
mss310
mss420f
mss110
