调试由另一EXE启动的EXE：C#项目空引用异常排查求助

Hey there! Let's walk through the common debugging approaches your predecessor likely used to tackle this exact scenario—since you're already familiar with troubleshooting NullReferenceExceptions, these steps will help you bridge the gap on how to debug the cross-process launch from exe1 to exe2.

1. Attach the Debugger Directly to exe2 After Launch #

• Open your solution in Visual Studio 2015. Once you run exe1 and it launches exe2, head to the top menu: Debug > Attach to Process.
• In the process list, find exe2.exe (make sure "Show processes from all users" is checked if needed) and click "Attach". Now trigger the action that causes the error—you'll hit any breakpoints you've set in exe2 and can inspect the call stack/object states directly.

2. Force exe2 to Prompt for a Debugger on Startup #

• If you want to catch the error right as exe2 starts, add this line early in exe2's Program.Main() method:

  System.Diagnostics.Debugger.Launch();
  

• When exe1 launches exe2, a dialog will pop up asking you to select a debugger (pick your open VS2015 instance). This lets you step through exe2's code from the very beginning, which is great if the null reference happens during initialization.

3. Validate Data/Context Passed from exe1 to exe2 #

NullReferenceExceptions here often stem from missing or invalid data passed from exe1:

• Check the code in exe1 that launches exe2 (look for Process.Start() calls). Verify it's passing the correct command-line arguments, setting the working directory properly, or sending any required IPC data.
• In exe2, add logging to record critical context:

  // Log all command-line arguments
  foreach (var arg in Environment.GetCommandLineArgs())
  {
      // Write each arg to your log system
  }
  // Log current working directory
  Logger.Log($"Current working directory: {Directory.GetCurrentDirectory()}");
  

• If exe2 relies on local files, the working directory might default to exe1's path instead of its own—this can cause file-loading failures that lead to null references.

4. Use Multi-Project Debugging in Visual Studio #

Your predecessor might have set up the solution to debug both exes simultaneously:

• Right-click your solution in the Solution Explorer > Properties.
• Under "Startup Project", select "Multiple startup projects".
• Set exe1 to "Start" and exe2 to "Start without debugging" (or "Start" if you want both debugged immediately)—adjust the order so exe1 launches first.
• Now when you start debugging, VS will automatically attach to both processes. When exe1 launches exe2, you can step through code in either project as needed.

5. Enhance Exception Logging to Get Full Context #

The current log only shows the top-level exception—expand it to get actionable details:

• In exe2's global exception handler (or wherever the error is being logged), replace the log entry with ex.ToString() instead of just the exception message. This will include the exact method, class, and even line number (if debug symbols are available) where the null reference occurred.
• If you don't have a global handler, add one in Program.Main():

  try
  {
      // Existing Main logic here
  }
  catch (Exception ex)
  {
      Logger.Log($"Fatal error details: {ex.ToString()}");
      throw;
  }
  

内容的提问来源于stack exchange，提问作者coinbird