Asp.net Core 2.0 WebApi与Kestrel报错，请求协助解析错误信息

Hey there, let's break down this error you're seeing and walk through actionable troubleshooting steps to resolve it. These specific errors relate to low-level communication issues between your ASP.NET Core WebAPI and SQL Server 2017—here's what you need to check:

What Do These Errors Mean? #

FrameConnection.ProcessRequestsAsync and UbReadCb are part of the SQL Server client driver's internal logic:

• UbReadCb is a callback function responsible for reading data from the SQL Server connection stream.
• FrameConnection.ProcessRequestsAsync handles asynchronous connection requests.

Together, they indicate a failure in the connection or data transfer between your WebAPI (hosted in IIS) and the SQL Server instance.

Troubleshooting Steps #

1. Verify SQL Server Connectivity & Permissions #

• First, test if you can connect to SQL Server 2017 from your local PC using SQL Server Management Studio (SSMS). If this fails, fix the SQL Server network settings first:
  • Open SQL Server Configuration Manager, enable the TCP/IP protocol under SQL Server Network Configuration.
  • Ensure SQL Server is set to allow remote connections (check server properties in SSMS under Connections).
• Confirm the IIS application pool identity has database access:
  • If using Integrated Security=True in your connection string, grant the app pool account (e.g., IIS AppPool\YourAppPoolName) db_datareader and db_datawriter permissions on your target database.
  • If using SQL Server authentication, double-check the username/password in your connection string and ensure the SQL login has the necessary database permissions.

2. Validate Your Connection String #

A misconfigured connection string is a common culprit. Double-check appsettings.json for issues:

• For Windows authentication (local SQL Server):

  "ConnectionStrings": {
    "DefaultConnection": "Server=.;Database=YourDatabaseName;Integrated Security=True;TrustServerCertificate=True;"
  }
  

• For SQL Server authentication:

  "ConnectionStrings": {
    "DefaultConnection": "Server=.;Database=YourDatabaseName;User Id=YourSqlUser;Password=YourSqlPassword;TrustServerCertificate=True;"
  }
  

The TrustServerCertificate=True flag helps bypass SSL certificate errors common in local/test environments.

3. Check IIS Deployment Configuration #

• Ensure you have the ASP.NET Core 2.0 Hosting Bundle installed on your local PC—this adds the ASP.NET Core Module required for IIS to host Core apps.
• Set your IIS application pool's .NET CLR Version to No Managed Code (ASP.NET Core doesn't rely on traditional .NET CLR).
• Verify the physical path of your WebAPI has read/execute permissions for the IIS app pool account.

4. Enable Detailed Logging for More Context #

Turn on verbose logging in your WebAPI to get specific error details:

• In Program.cs, configure logging to capture debug-level messages:

  public static IWebHost BuildWebHost(string[] args) =>
      WebHost.CreateDefaultBuilder(args)
          .ConfigureLogging(logging =>
          {
              logging.SetMinimumLevel(LogLevel.Debug);
              logging.AddConsole();
              logging.AddDebug();
          })
          .UseStartup<Startup>()
          .Build();
  

• Also check SQL Server's error logs (in SSMS under Management > SQL Server Logs) for connection failure entries that might pinpoint the root cause.

5. Update SQL Server Client Driver #

Older versions of the SQL client driver can have compatibility issues with SQL Server 2017. Update the Microsoft.Data.SqlClient NuGet package to a version compatible with ASP.NET Core 2.0 (stick to 2.x versions, as newer releases don't support Core 2.0).

Start with the connectivity and connection string checks—those are the most frequent fixes for this error. If you still run into issues, share the detailed logs you collect, and we can dig deeper!

内容的提问来源于stack exchange，提问作者MilkBottle