Not able to initialize config file in Selenium C#

Hello

I am having problem to initialize my config file when try to run the test case. Here is the message I got

Message:
System.Configuration.ConfigurationErrorsException : Configuration system failed to initialize.

this is my config file 

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<appSettings>
<add key="appurl" value="https://login.yahoo.com/?.src=ym&.lang=en-US&.intl=us&.done=https%3A%2F%2Fmail.yahoo.com%2Fd"/>
<add key="emailid_xpath" value="//input[@id='login-username']"/>
<add key="nextbtn_xpath" value="//input[@id='login-signin']"/>
<add key="gecodriver" value="D:\\Selenium with C#"/>
</appSettings>
</configuration>

I am following exactly the way it is shown in the training session. I am using  visual studio 2019 enterprise edition.