I now have the message that it’s time to Migrate to the new app. I’ve tried the new app many months ago and moved back to the legacy app. If I click the “Migrate” button in the Smartthings notification, will it remove the legacy app? remove the current configuration data? ignore routines? Will I be able to move back to the legacy app for it’s limited lifetime? Thanks for any info.
Bill
It converts routines to automations/scenes in the new app. It converts SHM and SHM rules to STHM and automations/scenes. It migrates smart locks over to smart lock guest access. You would lose the ability to use routines, and SHM in the Classic app. You also lose the ability to edit scenes from the Classic app. But you can continue to use the Classic app to control devices until the app is shut down in the coming months.
Thank you for your response. It helps me formulate my plan.
Bill
Any idea if it impacts Alexa?
It shouldn’t.
Just migrated over, the main thing for me was that the 2 automations triggered by my phone and a presence sensor went across minus the sensor. When I tried edit the automation, to add the sensor back in, it would only allow it to monitor the battery level of the sensor not its location. So for me the fix was to create 2 new automations which were then trigged by the phone and the sensor either being away or at home. Other than that it all appears to be working, fingers crossed.
What about DTH’s from the classic app? I’ve got devices I need support for…
If they have standard capabilities, they should work fine if the VID and MNMN have been added to the DTH. If your devices have custom attributes and commands, they will not function properly until we have full support for custom capabilities.
I’ve been using a Centralite 3400 keypad with the legacy app, but it does not work with the new app. Is anyone aware of a DTH or Smartapp that would allow this keypad to work with the new app? Or a recommendation for another keypad that works with the new app? Thanks.
I will add that my needs are simple. Arming/Disarming the STHM is the main need.
Bill
I’m not sure about that model, hopefully someone else will know. But @rboy has just released one for the new Ring keypad which works with the new V3 app. It has been verified to work for arm/disarm of STHM in the new app, although you do have to use virtual switches to get it to work. 
To add to what JD said, the Ring keypad is by far one of the best keypads we have used, it’s just brimming with features. However if you’re looking specifically for the Centralite keypad, you can look at this DTH:
I saw a previous reference to this DTH and the Centralite keypad that mentioned that yes it would work with the new app (STHM) for arming/disarming but it would require the use of virtual switches. I’m not familiar with this. Can you point me to some documentation that would help with that process?
-Bill
See the link JD had posted earlier, it has posts on how to use it with STHM and also on this topic:
Thanks so much for the help from JDRoberts and RBoy. I’ve migrated to the new app which I like. Our upstairs Centralite keypad allows us to arm/disarm the alarm for bedtime. Life is good. I’ll enjoy it while it lasts.
Bill
the migration is BUGGY — some of my routines weren’t migrated and the app crashed. had to do them manually.