Commerce manager checks throw System.UnauthorizedAccessException exception.

Exception is handled in Global.asax (redirect to Unauthorized.html page)

	void Application_Error(object sender, EventArgs e)
	{
		Exception ex = Server.GetLastError().GetBaseException();

		if (ex != null)
		{
			if (typeof(UnauthorizedAccessException) == ex.GetType())
			{
                Response.Redirect(String.Format("~/Apps/Shell/Pages/Unauthorized.html"));
			}
			else if (typeof(HttpException) == ex.GetType())
			{
				int errorCode = ((HttpException)ex).ErrorCode;
				if (errorCode == 500) // consider 500 a fatal exception
				{
					// Log the exception
					LogManager.GetLogger(GetType()).Fatal("Backend encountered unhandled error.", ex);
					return;
				}
			}
		}

		// Code that runs when an unhandled error occurs
		// Log the exception
		LogManager.GetLogger(GetType()).Error("Backend encountered unhandled error.", ex);

	}

From MSDN:

The exception that is thrown when the operating system denies access because of an I/O error or a specific type of security error.

Live case:

- Mediachase.Search.config

<Indexers basePath="[no accessible path]">

[not accessbile path] = path that current user(IIS application domain identity) can't access/read/write

- Go to Commerce Manager->Administration->System Settings->Search index

- Note the message: 

That is definetly wrong!

Commecer manager framework should use its' own custom security exception type and catch it to make redirect.

Using of system exceptions leads to total hiding of problem root and does really confuse users/developers!

Sorry for emotion, but I've just spent almost all day investigating the problem.