An error occurred while enumerating the groups. the group could not be found. : Get the Bad groups name.

Problem: An error occurred while enumerating the groups. the group could not be found.

In c#.net exception occurs. 

1. Then way to find the bad group. Below is the code.
2. First get all groups for a user in AD.
3. Then loop through and get the object of Group Name. If not found then it will be null.
4. Else it is a valid Group.
5. "nullgrpname" variable contains all Bad Groups.

private void GetBadGroups(string groupName, string userName)

    {

        System.DirectoryServices.AccountManagement.PrincipalContext ctx = new System.DirectoryServices.AccountManagement.PrincipalContext(

                                        System.DirectoryServices.AccountManagement.ContextType.Domain, "DOMAIN");

        // find a user

        System.DirectoryServices.AccountManagement.UserPrincipal uPrincipal = System.DirectoryServices.AccountManagement.UserPrincipal.FindByIdentity(ctx, userName);

        string res = "";

        var sroles = uPrincipal.GetAuthorizationGroups();

        if (sroles != null && sroles.Count() > 0)

        {

            int i = 0;

            List<string> rs = new List<string>();

            while (i < sroles.Count()) //unknown error happens on some groups

            {

                try

                {

                    var role = sroles.ElementAt(i);

                    if (role != null && role.Name != null)

                        rs.Add(role.Name.ToUpper());

                }

                catch

                {

                    res += ("A bad group has been found on user:" + userName);

                }

                i++;

            }

            string[] roles = rs.ToArray();

            string ab1 = roles[0];

            ////   ---------------------------------

            string nullgrpname = "";

            foreach (string name in roles)

            {

                groupName = name;

                // set up domain context

                PrincipalContext ctx1 = new PrincipalContext(ContextType.Domain, "DOMAIN");

                // find a user

                UserPrincipal user = UserPrincipal.FindByIdentity(ctx1, userName);

                // find the group in question

                GroupPrincipal group = GroupPrincipal.FindByIdentity(ctx1, groupName);

                if (group == null)

                {

                    nullgrpname += groupName + ";";

                }

                if (user != null && group != null)

                {

                    // check if user is member of that group

                    if (user.IsMemberOf(group))

                    {

                        // do something.....

                    }

                }

            }

        }

    }