Registry Value Change Error(Object reference not set to an instance of an object)

Question

I'am currently trying to make a little program, which changes my standard audio device from my USB Headset to my Speakers. After using Regshot to locate the registry keys that are changed by manually switching the audio devices, I was able to find out the binary codes for my Speaker and Headset.

static void Main(string[] args)
    {
        RegistryKey standarddevice = Registry.LocalMachine.OpenSubKey("SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\MMDevices\\Audio\\Render\\{02b3c792-0c05-486c-be02-2ded778dc236}", true);
        standarddevice.SetValue("Role:0", "DF 07 01 00 04 00 08 00 16 00 01 00 14 00 55 01", RegistryValueKind.Binary);
        standarddevice.SetValue("Role:1", "DF 07 01 00 04 00 08 00 16 00 01 00 14 00 55 01", RegistryValueKind.Binary);
        standarddevice.SetValue("Role:2", "DF 07 01 00 04 00 08 00 16 00 01 00 14 00 55 01", RegistryValueKind.Binary);
    }

The Problem, which I'am not able to solve, is that I get a "Object reference not set to an instance of an object" Error.

possible duplicate of [What is a NullReferenceException and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — pmcoltrane, Jan 09 '15 at 20:05

score 0 · Answer 1 · answered Jan 09 '15 at 20:01

0

Seems that your standarddevice object is null.

Why do I get the error "Object reference not set to an instance of an object"?

answered Jan 09 '15 at 20:01

andrewsha

177
3

Rufus L · Accepted Answer · 2015-01-09T20:13:25.310

It's most likely because the specified key does not exist.

Check out the documentation: http://msdn.microsoft.com/en-us/library/z9f66s0a(v=vs.110).aspx

OpenSubKey will return null if the Open operation fails.

To resolve this, you should check for null and do the appropriate thing, perhaps:

RegistryKey standarddevice = Registry.LocalMachine.OpenSubKey(
    "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\MMDevices\\Audio\\Render\\" + 
    "{02b3c792-0c05-486c-be02-2ded778dc236}", true);

if (standardDevice != null)
{
    standarddevice.SetValue("Role:0", 
        "DF 07 01 00 04 00 08 00 16 00 01 00 14 00 55 01", RegistryValueKind.Binary);
    standarddevice.SetValue("Role:1", 
        "DF 07 01 00 04 00 08 00 16 00 01 00 14 00 55 01", RegistryValueKind.Binary);
    standarddevice.SetValue("Role:2", 
        "DF 07 01 00 04 00 08 00 16 00 01 00 14 00 55 01", RegistryValueKind.Binary);
}

If you see that the key does actually exist, it's possibly under the Wow6432Node if you're on a 64-bit machine. In that case you can try something like:

RegistryKey standarddevice = Registry.LocalMachine.OpenSubKey(
    "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\MMDevices\\Audio\\Render\\" + 
    "{02b3c792-0c05-486c-be02-2ded778dc236}", true);

if (standardDevice == null)  
{
    standarddevice = Registry.LocalMachine.OpenSubKey(
       "SOFTWARE\\Wow6432Node\\Microsoft\\Windows\\CurrentVersion\\MMDevices\\" +
       "Audio\\Render\\{02b3c792-0c05-486c-be02-2ded778dc236}", true);
}

if (standardDevice != null)
{
    standarddevice.SetValue("Role:0", 
        "DF 07 01 00 04 00 08 00 16 00 01 00 14 00 55 01", RegistryValueKind.Binary);
    standarddevice.SetValue("Role:1", 
        "DF 07 01 00 04 00 08 00 16 00 01 00 14 00 55 01", RegistryValueKind.Binary);
    standarddevice.SetValue("Role:2", 
        "DF 07 01 00 04 00 08 00 16 00 01 00 14 00 55 01", RegistryValueKind.Binary);
}

Registry Value Change Error(Object reference not set to an instance of an object)

2 Answers2