Hi,
First, sorry for my bad english 
Since yesterday all my rules containing the function “SetLevel” to adjust my dimmer switch stopped working for no reason.
What was working the day before is now giving me this error in the log :
Failed to send device command.
If I change my rule to switch on or off my light, everything is working fine. The problem is really to set the level of the light.
I have the exact same issue with Globe Switch and TPLink KASA.
Anyone have an idea?
Thank you all!
Which hub/platform are your dimmer switches connected to?
If it’s SmartThings, I wonder if something changed with the Globe and TP Link integration or something else might have changed behind the scenes? If you add those devices to a dashboard, are you able to control the dim level successfully or does it also show an error sending the device command?
Feel free to PM @support with the Rule ID (or the Rule URL) and I would be happy to take a closer look as well.
OK,
I’m sending a PM now! 
Any updates on this? I may have to change all my setlevel rules to a simple on command 
Unfortunately, nothing helpful yet. The last update I got from the primary engineer I’m working with was yesterday at 2:57 p.m. CST:
“I am tracking something that could be related and hope to know more in a bit.”
Just wanted to provide an update that the issue the engineering team was tracking ended up not being the cause of the issue. The SmartThings engineering team indicated that they’ll be digging in further next week.
As a side note, SmartThings users have begun reporting the issue and the webCoRE community is reporting it as well, so it does appear to be a broader SmartThings platform issue as suspected.
Fyi, the problem seems to be fixed now!
Glad to hear things are working again! Users in the WebCoRE and SmartThings communities are reporting that things are working for them as well.