Why the exception page doesn't show details in Development environment in IDE-CodePudding

I am working on a custom error page for non-development environments. While working on this custom page, I set environment to "Staging" in launchSettings.json file. When I switched the setting back to "Development" and restarted the app, it only showed the generic error page (see following screenshot.)

I run the trace in program.cs and did see the it was using the default exception handler middleware: app.UseExceptionHandler("/Error");

I even existed the IDE and started again. But the detailed error page was no longer working. I could not figure out what caused this to happen and unable to resolved it. Please help! (see more details in following sections)

TESTING INFO:

App Type: ASP .NET6 with razor pages

IDE: VS 2022

Dev machine: Windows 11

Using IIS Express to view web pages

launchSettings.json

{
  "iisSettings": {
    "windowsAuthentication": false,
    "anonymousAuthentication": true,
    "iisExpress": {
      "applicationUrl": "http://localhost:16950",
      "sslPort": 44324
    }
  },
  "profiles": {
    "WebProtectConnString": {
      "commandName": "Project",
      "dotnetRunMessages": true,
      "launchBrowser": true,
      "applicationUrl": "https://localhost:7074;http://localhost:5074",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "development"
      }
    },
    "IIS Express": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "development"
      }
    }
  }
}

ERROR HANDLING CONFIG (in program.cs)

if (app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
}
else
{
    app.UseExceptionHandler("/Exceptions/ErrorHandler");
}

CodePudding user response：

By default, in Program.cs file of a .net 6 project, if (!app.Environment.IsDevelopment()) is the default code, but in your code snippet, it's if (app.Environment.IsDevelopment()), this means when you set Development in the launchSettings.json, your application will execute this 2 lines

app.UseExceptionHandler("/Error");
app.UseHsts();

And when execute app.UseExceptionHandler("/Error"); with an unhandled exception, the Error.cshtml will appear.. That's the reason you saw the page in your screenshot.

Since you want to use a custom view for non-development environments, you may need to remove app.UseExceptionHandler("/Error"); and write code below, this will make your app show exception message directly in development stage and show your custom view in other stages:

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Exceptions/ErrorHandler");
    app.UseHsts();
}else{ //leave the else empty, then exception will show in browser directly  }