配置系统无法初始化 - Windows服务

Question

我有一个Windows服务，需要在某个时间点发送电子邮件。 当我尝试初始化SmtpClient时，我收到错误“配置系统无法初始化”。

知道如何解决这个问题吗？

SMTP客户端初始化

 SmtpClient smtpClient = new SmtpClient();
 smtpClient.Port = Int32.Parse(smtpPort);
 smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
 smtpClient.EnableSsl = true;
 smtpClient.Host = smtpHost;

的App.config

<?xml version="1.0" encoding="utf-8" ?>
  <configuration>
    <startup>
      <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
    </startup>
    <!-- Log4Net Configuration -->
    <configSections>
      <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" requirePermission="false"/>
    </configSections>
    <log4net>
      <root>
        <level value="ALL" />
        <appender-ref ref="RollingFileAppender" />
      </root>
      <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
        <file value="Logs\ArchiveService.log" />
        <appendToFile value="true" />
        <rollingStyle value="Size" />
        <maxSizeRollBackups value="10" />
        <maximumFileSize value="10MB" />
        <staticLogFileName value="true" />
        <layout type="log4net.Layout.PatternLayout">
          <conversionPattern value="%date [%thread] %level - %message%newline" />
        </layout>
      </appender>
    </log4net>
    <appSettings>
    </appSettings>
  </configuration>