C# App.config问题（架构）

我的控制台应用程序中的app.config文件有此问题

这是我的app.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
      <section name="PROJECTNAME.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" />
    </sectionGroup>
  </configSections>
  <userSettings>
    <PROJECTNAME.Properties.Settings>
      <setting name="SETTING1" serializeAs="String">
        <value>stringvariable</value>
      </setting>
      <setting name="SETTING2" serializeAs="String">
        <value>boolvariable</value>
      </setting>
      <setting name="SETTING3" serializeAs="String">
        <value>intvariable</value>
      </setting>
    </PROJECTNAME.Properties.Settings>
  </userSettings>
</configuration>

信息3-6重复3次

如果我随后转到XML>Create schema，它会创建一个app.xsd，但随后它会给我另一个警告：

 Warning    1   The global element 'configuration' has already been declared.   App.xsd

我已经尝试解决这个问题好几天了，但没有结果。我无法用谷歌找到解决方案

 Warning    1   The global element 'configuration' has already been declared.   App.xsd