'More than one DbContext named 'NewProject.Models.DbContext' was found Specify which one to use by providing its fully qualified name using exact case

I was developing a Web-App with Asp.Net Core 2.1 . After I added the new identity with scaffolder it generated me these codes:

Code generated in IdentityStartup.cs

[assembly:HostingStartup(typeof(ShareAndCare.Areas.Identity.IdentityHostingStartup))]
namespace ShareAndCare.Areas.Identity
{
    public class IdentityHostingStartup : IHostingStartup
    {
        public void Configure(IWebHostBuilder builder)
        {
            builder.ConfigureServices((context, services) => {

                services.AddDbContext<ShareAndCareContext>(options =>
                   options.UseLazyLoadingProxies().UseSqlServer(
                       context.Configuration.GetConnectionString("ShareAndCareContextConnection")));

                services.AddIdentity<ShareAndCareUser, IdentityRole>()
                .AddEntityFrameworkStores<ShareAndCareContext>()
                .AddDefaultTokenProviders();

                services.AddSingleton<IEmailSender, EmailSender>();               

            });

        }
    }
}

Code generated in Startup.cs

    namespace ShareAndCare
    {
        public class Startup
        {
            public Startup(IConfiguration configuration)
            {
                Configuration = configuration;
            }

            public IConfiguration Configuration { get; }

            // This method gets called by the runtime. Use this method to add services to the container.
            public void ConfigureServices(IServiceCollection services)
            {
                services.Configure<CookiePolicyOptions>(options =>
                {
                    // This lambda determines whether user consent for non-essential cookies is needed for a given request.
                    options.CheckConsentNeeded = context => true;
                    options.MinimumSameSitePolicy = SameSiteMode.None;
                });            

                services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);            
            }    
            // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
            public void Configure(IApplicationBuilder app, IHostingEnvironment env, IServiceProvider serviceProvider)
            {
                if (env.IsDevelopment())
                {
                    app.UseDeveloperExceptionPage();
                }
                else
                {
                    app.UseExceptionHandler("/Home/Error");
                    app.UseHsts();
                }

                app.UseHttpsRedirection();
                app.UseStaticFiles();
                app.UseAuthentication();
                app.UseCookiePolicy();

                app.UseMvc(routes =>
                {
                    routes.MapRoute(
                        name: "default",
                        template: "{controller=Home}/{action=Index}/{id?}");
                });                
            }   
        }
    }

This was working fine until I wanted to scaffold a model with controller and views using EF. When set up everything and click ok I was getting an error saying : More than one DbContext named 'ShareAndCare.Models.ShareAndCareContext' was found. Specify which one to use by providing its fully qualified name using its exact case. I checked all the folders and namespaces but there was no problem there, there was only one context with that name. So what was the problem ?

c++sharpentity-frameworkasp.net-coreasp.net-mvc-scaffoldingasp.net-core-2.1


Solution 1:[1]

I just deleted the 2 files:

  1. Areas/Identity/Data/APNameIdentityDbContext.cs and
  2. Areas/Identity/IdentityHostingStartup.cs

This fixed the error!

Solution 2:[2]

In my Case I was adding services.AddDbContext<DBContext> but instead my DBContext name was

ApplicationDBContext.

Changed my Name in Startup.cs and it worked

 public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();
            services.AddDbContext<ApplicationDBContext>(options => options.UseSqlServer(Configuration["Data:ConnectionStrings:DefaultConnection"]));
        }

Hope this helps someone :)

Sources

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Source: Stack Overflow

Solution Source
Solution 1 DedicatedLearner
Solution 2 gouravm

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