ASP.NET Razor Pages error while processing the request

Question

I’m implementing an example using ASP.NET Razor Pages and when trying to access the page Index I have the error that there is error in the request.

Error. An error occurred while Processing your request. Request ID: 0HLA7N3BM0ANB:00000001

Development Mode Swapping to Development Detailed information about the error that occurred.

Development Environment should not be enabled in Deployed Applications, as it can result in sensitive information from exceptions being displayed to end users. For local debugging, Development Environment can be enabled by Setting the ASPNETCORE_ENVIRONMENT Environment variable to Development, and restarting the application.

Index.cshtml

@page
@model IndexModel
@{
    ViewData["Title"] = "Home page";
}

<h1>Contacts</h1>
<form method="post">
    <table class="table">
        <thead>
            <tr>
                <th>ID</th>
                <th>Name</th>
            </tr>
        </thead>
        <tbody>
            @foreach (var contact in Model.Customers)
            {
                <tr>
                    <td>@contact.Id</td>
                    <td>@contact.Name</td>
                    <td>
                        <a asp-page="./Edit" asp-route-id="@contact.Id">edit</a>
                        <button type="submit" asp-page-handler="delete" 
                                asp-route-id="@contact.Id">delete</button>
                    </td>
                </tr>
            }
        </tbody>
    </table>

    <a asp-page="./Create">Create</a>
</form>

Index.cshtml.Cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using RazorPagesContacts.Data;
using Microsoft.EntityFrameworkCore;

namespace RazorPagesContacts.Pages
{
    public class IndexModel : PageModel
    {
        private readonly AppDbContext _db;

        public IndexModel(AppDbContext db)
        {
            _db = db;
        }

        public IList<Customer> Customers { get; private set; }


        public async Task OnGetAsync() 
        {
            Customers = await _db.Customers.AsNoTracking().ToListAsync();   
        }

        public async Task<IActionResult> OnPostDeleteAsync(int id)
        {
            var contact = await _db.Customers.FindAsync(id);
            if(contact != null)
            {
                _db.Customers.Remove(contact);
                await _db.SaveChangesAsync();
            }

            return RedirectToPage();
        }

        public void OnGet()
        {

        }
    }
}

Answer 1

The error occurs because the Razor Page cannot know at runtime which of the two methods GET created in your code, that is to say, OnGet and OnGetAsync is to be executed, summarizing can not coexist the two at the same time in the code, because they do the same thing, generating an exception because of that.

_References

• Introduction to Razor Pages in ASP.NET Core
• ASP.NET Core - Simpler ASP.NET MVC Applications with Razor Pages

Answer 2

In the web.config change(or add if not available) the tag’s value environmentVariable for Development:

<environmentVariables>
        <environmentVariable name = "ASPNETCORE_ENVIRONMENT" value="Production" />
</environmentVariables>



<configuration>
  <!--
    Configure your application settings in appsettings.json.Learn more at http://go.microsoft.com/fwlink/?LinkId=786380
  -->
  <system.webServer>
    <handlers>
      <add name = "aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified" />
    </handlers>
    <aspNetCore processPath = ".\Application.exe" arguments="" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" forwardWindowsAuthToken="false">
      <environmentVariables>
        <environmentVariable name = "ASPNETCORE_ENVIRONMENT" value="Production" />
      </environmentVariables>
    </aspNetCore>
  </system.webServer>
</configuration>

Source: https://stackoverflow.com/questions/39737585/asp-net-core-deployment-to-iis-error-development-environment-should-not-be-enab

In case you don’t decide, just let me know.