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Hello everyone,
I am trying to add Folder Exclusion for Windows Defender using PowerShell through C#
This only works if the path is short, for example:
"C:\New folder"
If the path is a bit longer it doesn't work, for example:
"C:\New folder\New folder1"
What's the problem? Can someone help me please. Thank you.
Below is my code which works fine only if the folder path is short.

What I have tried:

private void addFolderToExclusion()
                FolderBrowserDialog fbd = new FolderBrowserDialog();
                if (fbd.ShowDialog() == System.Windows.Forms.DialogResult.OK)              
                string path = openFileDialog1.FileName;
                startInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
                startInfo.FileName = "powershell.exe";
                startInfo.Arguments = "-command \"Add-MpPreference -ExclusionPath " + path + "\"";
                process.StartInfo = startInfo;
Updated 1-Jan-23 14:08pm
PIEBALDconsult 10-Sep-22 12:00pm    
Same as here -- -- I expect.
Dave Kreskowiak 10-Sep-22 12:34pm    
If fails because you're path has spaces in it and you're not enclosing that path in quotes, "C:\New Folder\New Subfolder",

How many times do you have to be told: you need Admin rights to edit the LOCAL_MACHINE branch of the registry?

I told you that only three hours ago: Set the folder path in the registry - a problem ? C#[^] - and the situation hasn't changed in that time.

It doens't matter what app you try to use, you need UAC and admin permissions to do it.
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You have to use 'path' if the folder has a space in its name.
Try this:

startInfo.Arguments = "-command \"Add-MpPreference -ExclusionPath '" + path + "'\"";

Added ' before and after the path
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