[部分翻译]How to Fix Login failed for user 'IIS APPPOOL\ASP.NET v4.0' error in IIS7

haoman

　　今天用silverlight 4 调用ADO.NET Data Service(使用windows集成身份认证)，ADO.NET Data Service在windows7下的iis7.5上；结果出现了如标题这个错误。自己研究多时无果，故google之，发现只有英文解决办法。 错误信息大概如下：
　　Login failed for user 'IIS APPPOOL\ASP.NET v4.0'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: Login failed for user 'IIS APPPOOL\ASP.NET v4.0'.
　　
　　其实修改iis7.5中应用连接池的相关连接的标识为LocalSystem即可.
　　以下是英文原文的解决方法
　　Here's a step-by-step guide to determining your websites Application Pool, then changing its Process Model Idenitty in IIS7:

• Open Internet Information Services (IIS) Manger.
  
• In the Connections sidebar, drill down into Default Web Site and click on your website.
  
• Now in the Actions sidebar (on right side), click on Advance Settings... In the popup box, under General you will see your Application Pool listed for your website (in my case the app pool is: ASP.NET V4.0).
  
• Click Cancel...  If you choose, you can change the Application Pool here, but for the sake of this example we just wanted to find out what the website's App Pool was.
  

　　Now that we know the Application Pool that is configured for are website, we now want to change the app pool's (Process Model) Identity to 'NetworkService', here's how:

• Open Internet Information Services (IIS) Manger.
  
• In the Connections sidebar, click on Application Pools.
  
• Now right-click on theApplication Pool that your website is using (in this case my site is using the ASP.NET v4.0 application pool), and select Advanced Settings... from the menu.
  
• In the Advanced Settings pop-up box, locate the Process Model -> Identity section and click on the Application Pool Identity.
  
• In the Application Pool Identity pop-up box, change the Built-in account to NetworkService (or if you want LocalSystem), then click OK, and click OK again to save your Advanced Settings changes.
  

　　After changing the Application Pool's Identity to NetworkService (or LocalSystem) you should now be able to get your ASP.NET site to run successfully on a IIS7 web server:
　　
　　
　　原文地址：http://www.gotknowhow.com/articles/fix-login-failed-for-user-iis-apppool-aspnet-v4-error-iis7