"access to keychain forbidden" while adding CalDav account

Question

My problems started when a client's mobile account became disabled after the open directory locked them out.  I was able to "unlock" the account by deleting the a keychain (somehow, I am not so good documenting while under pressure). 
Unfortunately, none of their passwords could be saved aftewards.  Most noticebly, I couldn't add a CalDav account to iCal and kept giving me an "incorrect login username or password". 
What I eventually figured out after hours of frustration:  there should be 3 keychains: "login", "system" and "System roots" in the "Keychain Access" utility! My problem was I only had the "system" and "System roots" keychains showing up in the upper left pane.
To add a missing keychain:
Go to "File"-->"New Keychain"-->call it what you'd like --> "Create"
Make sure you remember the password!! 
Hope this helps anyone else who comes across this problem.

Answer 1

Hi Jitendra,
You are required to call web.EnsureUser function to ensure if user exists in web and if not then add it into the web before adding it into the group.
User csvUser = context.Web.EnsureUser(strLoginName);
context.Load(csvUser);
context.ExecuteQuery();
selectedGroup.Users.AddUser(csvUser);
selectedGroup.Update();
context.ExecuteQuery();
Below is the link to project hosted on codeplex for adding users using CSV file using client object model. You can check the code also.
https://sharepointuserhelper.codeplex.com/
Hope this will help to solve your problem.
Best Regards,
Brij K