SqlConnection 错误 "Object reference not set to an instance of an object."

Question

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["TropicalConnectionString"].ConnectionString);

它说

Object reference not set to an instance of an object.

为了检查错误，我给出了我的 app.config，我想知道我是否为 Initial Catalog 等提供了错误的名称？

这是我的 app.config:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <connectionStrings>
        <add name="TropicalConnectionString" 
             connectionString="Data Source = JIRAN-PC; Initial Catalog = TropicalServer; Integrated Security = True"
             providerName="System.Data.SqlClient" />
        <add name="TropicalServiceWinApp.Properties.Settings.TropicalConnectionString"
             connectionString="Data Source=JIRAN-PC;Initial Catalog=TropicalServer;Integrated Security=True"
             providerName="System.Data.SqlClient" />
    </connectionStrings>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
    </startup>
    <system.serviceModel>
        <bindings>
            <basicHttpBinding>
                <binding name="BasicHttpBinding_ITropicalService" />
            </basicHttpBinding>
        </bindings>
        <client>
            <endpoint address="http://localhost:5483/TropicalService.svc"
                binding="basicHttpBinding" bindingConfiguration="BasicHttpBinding_ITropicalService"
                contract="TropicalServiceRef.ITropicalService" name="BasicHttpBinding_ITropicalService" />
        </client>
    </system.serviceModel>
</configuration>

Answer 1

试试这个：

Select 解决方案资源管理器中的 App.Config 文件
在属性 window select 复制到输出目录以始终复制。
现在构建应用程序并重试。

SqlConnection 错误 "Object reference not set to an instance of an object."

Error "Object reference not set to an instance of an object." for SqlConnection

c#

sql

sqlconnection