The client certificate is not provided. specify a client certificate in clientcredentials.

I have done all the setup; require to setup WCF message security and tried calling service from client, is working fine without any issues.
later I made few changes on the service and again use 'Update Service Reference' to update my service. suddenly service stop working and gave below error
 "The client certificate is not provided. specify a client certificate in clientcredentials."

Cause
As soon as I did service update; client side config file updated with new endpoint section, that removed (custom) one attribute 'behaviorConfiguration'.

Solution
After updating the service reference add 'behaviorConfiguration' attribute to endpoint section like below

<endpoint 

address="http://localhost:65514/Service1.svc" 

binding="wsHttpBinding"

bindingConfiguration="WSHttpBinding_IService1" 

contract="ServiceReference1.IService1"

name="WSHttpBinding_IService1"

behaviorConfiguration="CustomBehavior">

If you have added any kinds of attributes; that will be removed after you update service using 'Update Service Reference'.