ask user what to on optimistic concurrency in efcore

Question

I need to implement optimistic concurrency in efcore in a n-layer application, when an exception of type DbUpdateConcurrencyException occurs, the user must be asked if he wants to save the changes sent by him or discard them, exception handling is done from a repository class in the DAL.  How would they do it? It must be consumed from a web application and WPF.I know that I must implement an event but I have tried creating a helper that triggers when there is an exception and communicates with the controller but does not work.