Following the Contact Book deprecation on July 31st 2018, webCoRE v0.3.106.20180731 and later provides a way for users to automatically redirect all Contact Book requests to PUSH notifications - this is not optimal, as more people could receive notifications than initially intended, so the option is turned off in the SmartApp’s settings. Enabling it would allow you to continue receiving the notifications, but be aware that other people (those sharing your account) can start receiving them too. Best to visit each piston that uses the now defunct Contact Book and replace that task with a SMS notification, most likely. Please update to the latest version to avoid issues with the Contact Book still being referenced.
SmartThings has completely removed the Contact Book feature on July 31st, 2018
TRDeadbeat
#2
@ady624
Do you and the team have any creative solutions on the horizon to work around this awful change made by the ST team (outside of the SMS option)?
Please say you have a light at the end of the tunnel for us 
ChicoQuente
#3
I also have my fingers crossed that there is a solution to this. SMS option seems awful to me. What a poor decision on SmartThing’s part. I used this feature heavily in my pistons and am very disappointed to see it go. I hope someone smarter than I comes up with a good resolution to this.