Question

I have an application that needs to delete a subkey tree and readd the entries. The tree may have values changed or additional values added and I need to reset to the default state. When I delete the subtree with key.DeleteSubKeyTree() everything works great until I attempt to readd the base registry settings. At this point I get Illegal Operation error (illegal operation attempted on a registry key that has been marked for deletion).

So, how can I close/flush the deleted entries? Looks like all the delete operations operate on subkeys/values by name, not reference so I can’t directly close it. I am closing the root key.

Due to the values that may have been added, I do need to delete and not just set the values so the added keys (ones not in the base registry) are cleared from the registry.

Answer 1

After a little more experimentation, I was able to perform the task by indvidually deleting all the values and then deleting the subkeys. Here’s a recursive routine to do it:

     /// <summary>
     /// Deletes all the values and subkeys of a particular key.
     /// </summary>
     /// <param name="key"></param>
     private static void DeleteRegistrySubStructure(RegistryKey key)
     {
         // First, traverse the subkeys to delete the underlying values and subkeys.
         String[] subKeys = key.GetSubKeyNames();
         foreach (var subKeyName in subKeys)
         {
             RegistryKey subKey = key.OpenSubKey(subKeyName, true);
             DeleteRegistrySubStructure(subKey);
             subKey.Close();
             key.DeleteSubKey(subKeyName);
         }

         // At this point, all the subkeys (and their values) have been 
         // deleted.  So, delete the values for the key for final clean up. 
         string[] valueNames = key.GetValueNames();
         foreach (string name in valueNames)
         {                
             key.DeleteValue(name);
         }
     }