system.NullReferenceException 未将对象引用设置到对象的实例

Question

conn.ConnectionString=ConfigurationManager.ConnectionStrings["shopConnectionString"].ToString();

Answer 1

Web.config <connectionStrings>不存在名称为shopConnectionString的项，检查下web.config文件

  <connectionStrings>
    <add name="shopConnectionString" connectionString="数据库连接字符串" providerName="System.Data.SqlClient"/>
  </connectionStrings>