How to recursively delete Registry Key using DeleteSubkeyTree

Question

Code:

try 
{
     RegistryKey SQMRegKey = Registry.LocalMachine.OpenSubKey("CurrentControlSet\\Control\\WMI\\Autologger", true);
     //SQMRegKey.DeleteSubKey("SQMLogger");
     SQMRegKey.DeleteSubKeyTree("SQMLogger");
     SQMRegKey.Close();
} 
catch (Exception ex)
{
     MessageBox.Show(this, ex.ToString());
}

always throws exception System.NullReferenceException:Object reference not set to an instance of an object

Possible duplicate of [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — D-Shih, Oct 05 '18 at 11:15

score 0 · Answer 1 · answered Oct 05 '18 at 11:57

OpenSubKey may fail, in which case the return value is null. You use the reference, i.e. SQMRegKey without checking if it actually points to a valid object.

try 
{
     var SQMRegKey = Registry.LocalMachine.OpenSubKey("CurrentControlSet\\Control\\WMI\\Autologger", true);
     if(SQMRegKey != null)
     {
        SQMRegKey.DeleteSubKeyTree("SQMLogger");
        SQMRegKey.Close();
     }
} 
catch (Exception ex)
{
     MessageBox.Show(this, ex.ToString());
}

I take note of the reference to the null value and will look to using != or GetValue method — wolfen, Oct 05 '18 at 13:18

A. Gopal Reddy · Accepted Answer · 2018-10-05T12:44:13.723

0

The registry path is not correct. Please use the below modified code:

        try
        {
            RegistryKey SQMRegKey = Registry.LocalMachine.OpenSubKey("System\\CurrentControlSet\\Control\\WMI\\Autologger", true);
            //SQMRegKey.DeleteSubKey("SQMLogger");

            SQMRegKey.DeleteSubKeyTree("SQMLogger");

            SQMRegKey.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }

edited Oct 05 '18 at 12:44

answered Oct 05 '18 at 12:33

A. Gopal Reddy

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Thanks that did it , you were correct I missed the system – wolfen Oct 05 '18 at 13:15

How to recursively delete Registry Key using DeleteSubkeyTree

2 Answers2