Error while creating CMK(column master key) in always encrypted I am trying to explore SQL 2016 always encrypted feature but i am getting an error while generating new column master key, after entering name and selecting 'Windows Certificate Store-Current User' as key store through SSMS when i click on ok its throwing an error as  object reference not set to an instance sql(sqlmanagerui) 
 I googled it and checked the permission on registry but unable to solve this.
These kind of errors occur when there is something corrupt in windows, so please try repair sql server by running setup and also please do check if there is any pending reboot or an updates pending.
I have face same kind of problem and it was due to pending update so its something to deal with the registry