app.config中增加appSettings節點，conn.open時報初始化錯誤

在app.config中增加appSettings節點后，運行到conn.open時報如下錯誤：

    “System.Transactions.Diagnostics.DiagnosticTrace”的類型初始值設定項引發異常。”

將configSections節點放到configuration下的第一元素后問題解決，原因未知。

app.config改動前：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <appSettings>
        <add key="busCity" value="上海,東莞,中山,麗水,樂山,佛山,保定,北海,南京,南充,南寧,南通,臺州,合肥,唐山,安陽,宜賓,巴中,常州,常德,廣元,廣 州,德陽,惠州,成都,揚州,攀枝花,昆明,昭通,杭州,汕頭,江門,泰州,瀘州,淮安,深圳,清遠,煙臺,玉林,珠海,蘇州,衢州,達州,遂寧,鄭州, 重慶,鎮江,長沙,陽江,雅安,青島,韶關"/>
        <add key="busId" value="398328,595874,662326,280787,352434,601492,357595,355542,293437,390110,354921,489828,280796,390186,622586,338884,352959,347956,283053,376904,351940,662530,351110,662499,348289,690040,390582,609990,621734,277073,673785,666466,327372,354010,282585,635260,666754,398034,357334,556102,611718,281511,352419,351093,347918,399907,419461,359516,655530,351904,397721,674569"/>
    </appSettings>

    <configSections>
        <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
            <section name="TrainTickets.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" />
        </sectionGroup>
    </configSections>
   
</configuration>

app.config改動后：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>

      <configSections>
        <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
            <section name="TrainTickets.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" />
        </sectionGroup>
    </configSections>    <appSettings>
        <add key="busCity" value="上海,東莞,中山,麗水,樂山,佛山,保定,北海,南京,南充,南寧,南通,臺州,合肥,唐山,安陽,宜賓,巴中,常州,常德,廣元,廣 州,德陽,惠州,成都,揚州,攀枝花,昆明,昭通,杭州,汕頭,江門,泰州,瀘州,淮安,深圳,清遠,煙臺,玉林,珠海,蘇州,衢州,達州,遂寧,鄭州, 重慶,鎮江,長沙,陽江,雅安,青島,韶關"/>
        <add key="busId" value="398328,595874,662326,280787,352434,601492,357595,355542,293437,390110,354921,489828,280796,390186,622586,338884,352959,347956,283053,376904,351940,662530,351110,662499,348289,690040,390582,609990,621734,277073,673785,666466,327372,354010,282585,635260,666754,398034,357334,556102,611718,281511,352419,351093,347918,399907,419461,359516,655530,351904,397721,674569"/>
    </appSettings>

   
   
</configuration>