diff --git a/Kyoo.Authentication/AuthenticationModule.cs b/Kyoo.Authentication/AuthenticationModule.cs
index 02a0f982..559517d2 100644
--- a/Kyoo.Authentication/AuthenticationModule.cs
+++ b/Kyoo.Authentication/AuthenticationModule.cs
@@ -70,6 +70,8 @@ namespace Kyoo.Authentication
 		{
 			string publicUrl = _configuration.GetValue<string>("public_url").TrimEnd('/');
 
+			services.AddControllers();
+
 			// services.AddDbContext<IdentityDatabase>(options =>
 			// {
 			// 	options.UseNpgsql(_configuration.GetDatabaseConnection("postgres"));
@@ -84,6 +86,8 @@ namespace Kyoo.Authentication
 			// 	.AddEntityFrameworkStores<IdentityDatabase>();
 
 			services.Configure<PermissionOption>(_configuration.GetSection(PermissionOption.Path));
+			services.Configure<CertificateOption>(_configuration.GetSection(CertificateOption.Path));
+			services.Configure<AuthenticationOption>(_configuration.GetSection(AuthenticationOption.Path));
 			CertificateOption certificateOptions = new();
 			_configuration.GetSection(CertificateOption.Path).Bind(certificateOptions);
 
diff --git a/Kyoo.Authentication/Models/DTO/AccountUpdateRequest.cs b/Kyoo.Authentication/Models/DTO/AccountUpdateRequest.cs
index 4ec474d5..ac135799 100644
--- a/Kyoo.Authentication/Models/DTO/AccountUpdateRequest.cs
+++ b/Kyoo.Authentication/Models/DTO/AccountUpdateRequest.cs
@@ -11,13 +11,13 @@ namespace Kyoo.Authentication.Models.DTO
 		/// <summary>
 		/// The new email address of the user
 		/// </summary>
-		[EmailAddress]
+		[EmailAddress(ErrorMessage = "The email is invalid.")]
 		public string Email { get; set; }
 		
 		/// <summary>
 		/// The new username of the user.
 		/// </summary>
-		[MinLength(4)]
+		[MinLength(4, ErrorMessage = "The username must have at least 4 characters")]
 		public string Username { get; set; }
 		
 		/// <summary>
diff --git a/Kyoo.Authentication/Models/DTO/RegisterRequest.cs b/Kyoo.Authentication/Models/DTO/RegisterRequest.cs
index 4d8efa2c..ad556f6d 100644
--- a/Kyoo.Authentication/Models/DTO/RegisterRequest.cs
+++ b/Kyoo.Authentication/Models/DTO/RegisterRequest.cs
@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using Kyoo.Models;
 
@@ -11,19 +12,19 @@ namespace Kyoo.Authentication.Models.DTO
 		/// <summary>
 		/// The user email address
 		/// </summary>
-		[EmailAddress]
+		[EmailAddress(ErrorMessage = "The email must be a valid email address")]
 		public string Email { get; set; }
 		
 		/// <summary>
 		/// The user's username. 
 		/// </summary>
-		[MinLength(4)]
+		[MinLength(4, ErrorMessage = "The username must have at least {1} characters")]
 		public string Username { get; set; }
 		
 		/// <summary>
 		/// The user's password.
 		/// </summary>
-		[MinLength(8)]
+		[MinLength(8, ErrorMessage = "The password must have at least {1} characters")]
 		public string Password { get; set; }
 
 
@@ -38,7 +39,8 @@ namespace Kyoo.Authentication.Models.DTO
 				Slug = Utility.ToSlug(Username),
 				Username = Username,
 				Password = Password,
-				Email = Email
+				Email = Email,
+				ExtraData = new Dictionary<string, string>()
 			};
 		}
 	}	
diff --git a/Kyoo.Authentication/Models/Options/AuthenticationOptions.cs b/Kyoo.Authentication/Models/Options/AuthenticationOption.cs
similarity index 94%
rename from Kyoo.Authentication/Models/Options/AuthenticationOptions.cs
rename to Kyoo.Authentication/Models/Options/AuthenticationOption.cs
index f35e22a3..23e917aa 100644
--- a/Kyoo.Authentication/Models/Options/AuthenticationOptions.cs
+++ b/Kyoo.Authentication/Models/Options/AuthenticationOption.cs
@@ -3,7 +3,7 @@ namespace Kyoo.Authentication.Models
 	/// <summary>
 	/// The main authentication options.
 	/// </summary>
-	public class AuthenticationOptions
+	public class AuthenticationOption
 	{
 		/// <summary>
 		/// The path to get this option from the root configuration.
diff --git a/Kyoo.Authentication/Views/AccountApi.cs b/Kyoo.Authentication/Views/AccountApi.cs
index 903c7e93..bd49da94 100644
--- a/Kyoo.Authentication/Views/AccountApi.cs
+++ b/Kyoo.Authentication/Views/AccountApi.cs
@@ -2,18 +2,20 @@ using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
+using System.Linq;
 using System.Threading.Tasks;
 using IdentityServer4.Extensions;
 using IdentityServer4.Models;
 using IdentityServer4.Services;
+using Kyoo.Authentication.Models;
 using Kyoo.Authentication.Models.DTO;
 using Kyoo.Controllers;
 using Kyoo.Models;
+using Kyoo.Models.Exceptions;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Options;
-using AuthenticationOptions = Kyoo.Authentication.Models.AuthenticationOptions;
 
 namespace Kyoo.Authentication.Views
 {
@@ -32,7 +34,7 @@ namespace Kyoo.Authentication.Views
 		/// <summary>
 		/// The identity server interaction service to login users.
 		/// </summary>
-		private readonly IIdentityServerInteractionService _interaction;
+		// private readonly IIdentityServerInteractionService _interaction;
 		/// <summary>
 		/// A file manager to send profile pictures
 		/// </summary>
@@ -41,7 +43,7 @@ namespace Kyoo.Authentication.Views
 		/// <summary>
 		/// Options about authentication. Those options are monitored and reloads are supported.
 		/// </summary>
-		private readonly IOptionsMonitor<AuthenticationOptions> _options;
+		private readonly IOptions<AuthenticationOption> _options;
 
 
 		/// <summary>
@@ -52,12 +54,12 @@ namespace Kyoo.Authentication.Views
 		/// <param name="files">A file manager to send profile pictures</param>
 		/// <param name="options">Authentication options (this may be hot reloaded)</param>
 		public AccountApi(IUserRepository users,
-			IIdentityServerInteractionService interaction,
+			// IIdentityServerInteractionService interaction,
 			IFileManager files,
-			IOptionsMonitor<AuthenticationOptions> options)
+			IOptions<AuthenticationOption> options)
 		{
 			_users = users;
-			_interaction = interaction;
+			// _interaction = interaction;
 			_files = files;
 			_options = options;
 		}
@@ -69,15 +71,23 @@ namespace Kyoo.Authentication.Views
 		/// <param name="request">The DTO register request</param>
 		/// <returns>A OTAC to connect to this new account</returns>
 		[HttpPost("register")]
-		public async Task<ActionResult<string>> Register([FromBody] RegisterRequest request)
+		public async Task<IActionResult> Register([FromBody] RegisterRequest request)
 		{
 			User user = request.ToUser();
-			user.Permissions = _options.CurrentValue.Permissions.NewUser;
+			user.Permissions = _options.Value.Permissions.NewUser;
 			user.Password = PasswordUtils.HashPassword(user.Password);
 			user.ExtraData["otac"] = PasswordUtils.GenerateOTAC();
 			user.ExtraData["otac-expire"] = DateTime.Now.AddMinutes(1).ToString("s");
-			await _users.Create(user);
-			return user.ExtraData["otac"];
+			try
+			{
+				await _users.Create(user);
+			}
+			catch (DuplicatedItemException)
+			{
+				return Conflict(new {Errors = new {Duplicate = new[] {"A user with this name already exists"}}});
+			}
+
+			return Ok(new {Otac = user.ExtraData["otac"]});
 		}
 
 		/// <summary>
@@ -103,10 +113,10 @@ namespace Kyoo.Authentication.Views
 		[HttpPost("login")]
 		public async Task<IActionResult> Login([FromBody] LoginRequest login)
 		{
-			AuthorizationRequest context = await _interaction.GetAuthorizationContextAsync(login.ReturnURL);
+			// AuthorizationRequest context = await _interaction.GetAuthorizationContextAsync(login.ReturnURL);
 			User user = await _users.Get(x => x.Username == login.Username);
 
-			if (context == null || user == null)
+			if (user == null)
 				return Unauthorized();
 			if (!PasswordUtils.CheckPassword(login.Password, user.Password))
 				return Unauthorized();
@@ -122,7 +132,9 @@ namespace Kyoo.Authentication.Views
 		[HttpPost("otac-login")]
 		public async Task<IActionResult> OtacLogin([FromBody] OtacRequest otac)
 		{
-			User user = await _users.Get(x => x.ExtraData["OTAC"] == otac.Otac);
+			// TODO once hstore (Dictionary<string, string> accessor) are supported, use them.
+			//      We retrieve all users, this is inefficient.
+			User user = (await _users.GetAll()).FirstOrDefault(x => x.ExtraData.GetValueOrDefault("otac")  == otac.Otac);
 			if (user == null)
 				return Unauthorized();
 			if (DateTime.ParseExact(user.ExtraData["otac-expire"], "s", CultureInfo.InvariantCulture) <= DateTime.UtcNow)
@@ -166,7 +178,7 @@ namespace Kyoo.Authentication.Views
 			User user = await _users.GetOrDefault(slug);
 			if (user == null)
 				return NotFound();
-			string path = Path.Combine(_options.CurrentValue.ProfilePicturePath, user.ID.ToString());
+			string path = Path.Combine(_options.Value.ProfilePicturePath, user.ID.ToString());
 			return _files.FileResult(path);
 		}
 		
@@ -182,7 +194,7 @@ namespace Kyoo.Authentication.Views
 				user.Username = data.Username;
 			if (data.Picture?.Length > 0)
 			{
-				string path = Path.Combine(_options.CurrentValue.ProfilePicturePath, user.ID.ToString());
+				string path = Path.Combine(_options.Value.ProfilePicturePath, user.ID.ToString());
 				await using Stream file = _files.NewFile(path);
 				await data.Picture.CopyToAsync(file);
 			}
@@ -192,7 +204,7 @@ namespace Kyoo.Authentication.Views
 		[HttpGet("permissions")]
 		public ActionResult<IEnumerable<string>> GetDefaultPermissions()
 		{
-			return _options.CurrentValue.Permissions.Default;
+			return _options.Value.Permissions.Default;
 		}
 	}
 }
\ No newline at end of file
diff --git a/Kyoo.CommonAPI/DatabaseContext.cs b/Kyoo.CommonAPI/DatabaseContext.cs
index 584230b9..6b1bac47 100644
--- a/Kyoo.CommonAPI/DatabaseContext.cs
+++ b/Kyoo.CommonAPI/DatabaseContext.cs
@@ -8,6 +8,7 @@ using Kyoo.Models;
 using Kyoo.Models.Exceptions;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.ChangeTracking;
+using Microsoft.EntityFrameworkCore.Diagnostics;
 
 namespace Kyoo
 {
diff --git a/Kyoo.Postgresql/PostgresModule.cs b/Kyoo.Postgresql/PostgresModule.cs
index 7a818296..506f6dbe 100644
--- a/Kyoo.Postgresql/PostgresModule.cs
+++ b/Kyoo.Postgresql/PostgresModule.cs
@@ -63,7 +63,7 @@ namespace Kyoo.Postgresql
 			services.AddDbContext<DatabaseContext, PostgresContext>(x =>
 			{
 				x.UseNpgsql(_configuration.GetDatabaseConnection("postgres"));
-				if (_environment.IsDevelopment())
+				if (_configuration.GetValue<bool>("logging:dotnet-ef"))
 					x.EnableDetailedErrors().EnableSensitiveDataLogging();
 			});
 			// services.AddScoped<DatabaseContext>(_ => new PostgresContext(
diff --git a/Kyoo.WebLogin/login.js b/Kyoo.WebLogin/login.js
index 36ff3697..973128c8 100644
--- a/Kyoo.WebLogin/login.js
+++ b/Kyoo.WebLogin/login.js
@@ -41,11 +41,11 @@ $("#login-btn").on("click", function (e)
 			success: function ()
 			{
 				let returnUrl = new URLSearchParams(window.location.search).get("ReturnUrl");
-				
+
 				if (returnUrl == null)
 					window.location.href = "/unauthorized";
 				else
-					window.location.href = returnUrl;	
+					window.location.href = returnUrl;
 			},
 			error: function(xhr)
 			{
@@ -56,7 +56,7 @@ $("#login-btn").on("click", function (e)
 		});
 });
 
-$("#register-btn").on("click", function (e) 
+$("#register-btn").on("click", function (e)
 {
 	e.preventDefault();
 
@@ -73,7 +73,7 @@ $("#register-btn").on("click", function (e)
 		error.text("Passwords don't match.");
 		return;
 	}
-	
+
 	$.ajax(
 	{
 		url: "/api/account/register",
@@ -81,19 +81,19 @@ $("#register-btn").on("click", function (e)
 		contentType: 'application/json;charset=UTF-8',
 		dataType: 'json',
 		data: JSON.stringify(user),
-		success: function(res) 
+		success: function(res)
 		{
 			useOtac(res.otac);
 		},
-		error: function(xhr) 
+		error: function(xhr)
 		{
 			let error = $("#register-error");
 			error.show();
-			error.text(JSON.parse(xhr.responseText)[0].description);
+			error.html(Object.values(JSON.parse(xhr.responseText).errors).map(x => x[0]).join("<br/>"));
 		}
 	});
 });
-	
+
 function useOtac(otac)
 {
 	$.ajax(
@@ -101,7 +101,7 @@ function useOtac(otac)
 		url: "/api/account/otac-login",
 		type: "POST",
 		contentType: 'application/json;charset=UTF-8',
-		data: JSON.stringify({otac: otac, tayLoggedIn: $("#stay-logged-in")[0].checked}),
+		data: JSON.stringify({otac: otac, stayLoggedIn: $("#stay-logged-in")[0].checked}),
 		success: function()
 		{
 			let returnUrl = new URLSearchParams(window.location.search).get("ReturnUrl");
@@ -124,4 +124,4 @@ function useOtac(otac)
 
 let otac = new URLSearchParams(window.location.search).get("otac");
 if (otac != null)
-	useOtac(otac);
\ No newline at end of file
+	useOtac(otac);
diff --git a/Kyoo/Controllers/Repositories/UserRepository.cs b/Kyoo/Controllers/Repositories/UserRepository.cs
index 97bce050..5ebd4d2b 100644
--- a/Kyoo/Controllers/Repositories/UserRepository.cs
+++ b/Kyoo/Controllers/Repositories/UserRepository.cs
@@ -41,6 +41,15 @@ namespace Kyoo.Controllers
 				.Take(20)
 				.ToListAsync();
 		}
+		
+		/// <inheritdoc />
+		public override async Task<User> Create(User obj)
+		{
+			await base.Create(obj);
+			_database.Entry(obj).State = EntityState.Added;
+			await _database.SaveChangesAsync($"Trying to insert a duplicated user (slug {obj.Slug} already exists).");
+			return obj;
+		}
 
 		/// <inheritdoc />
 		public override async Task Delete(User obj)
diff --git a/Kyoo/Kyoo.csproj b/Kyoo/Kyoo.csproj
index 5804420f..7c39d8d3 100644
--- a/Kyoo/Kyoo.csproj
+++ b/Kyoo/Kyoo.csproj
@@ -45,7 +45,7 @@
 	
 	<ItemGroup>
 		<ProjectReference Include="../Kyoo.Authentication/Kyoo.Authentication.csproj">
-			<ExcludeAssets>all</ExcludeAssets>
+<!--			<ExcludeAssets>all</ExcludeAssets>-->
 		</ProjectReference>
 	</ItemGroup>
 	
diff --git a/Kyoo/Startup.cs b/Kyoo/Startup.cs
index 3c7ac57e..0054c066 100644
--- a/Kyoo/Startup.cs
+++ b/Kyoo/Startup.cs
@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using Kyoo.Authentication;
 using Kyoo.Controllers;
 using Kyoo.Models;
 using Kyoo.Postgresql;
@@ -46,7 +47,7 @@ namespace Kyoo
 			_configuration = configuration;
 			_plugins = new PluginManager(hostProvider, _configuration, loggerFactory.CreateLogger<PluginManager>());
 			
-			_plugins.LoadPlugins(new IPlugin[] {new CoreModule(), new PostgresModule(configuration, host)});
+			_plugins.LoadPlugins(new IPlugin[] {new CoreModule(), new PostgresModule(configuration, host), new AuthenticationModule(configuration, loggerFactory)});
 		}
 
 		/// <summary>
@@ -126,19 +127,20 @@ namespace Kyoo
 			app.UseResponseCompression();
 			
 			_plugins.ConfigureAspnet(app);
-			//
-			// app.UseSpa(spa =>
-			// {
-			// 	spa.Options.SourcePath = Path.Join(AppDomain.CurrentDomain.BaseDirectory, "Kyoo.WebApp");
-			//
-			// 	if (env.IsDevelopment())
-			// 		spa.UseAngularCliServer("start");
-			// });
-			
+
 			app.UseEndpoints(endpoints =>
 			{
 				endpoints.MapControllerRoute("Kyoo", "api/{controller=Home}/{action=Index}/{id?}");
 			});
+			
+			
+			app.UseSpa(spa =>
+			{
+				spa.Options.SourcePath = Path.Join(AppDomain.CurrentDomain.BaseDirectory, "Kyoo.WebApp");
+			
+				if (env.IsDevelopment())
+					spa.UseAngularCliServer("start");
+			});
 		}
 	}
 }
diff --git a/Kyoo/settings.json b/Kyoo/settings.json
index b521f8a8..cc213cc0 100644
--- a/Kyoo/settings.json
+++ b/Kyoo/settings.json
@@ -20,8 +20,12 @@
       "default": "Trace",
       "Microsoft": "Warning",
       "Microsoft.Hosting.Lifetime": "Information",
+      "Microsoft.EntityFrameworkCore.DbUpdateException": "None",
+      "Microsoft.EntityFrameworkCore.Update": "None",
+      "Microsoft.EntityFrameworkCore.Database.Command": "None",
       "Kyoo": "Trace"
-    }
+    },
+    "dotnet-ef": "false"
   },
   
   "authentication": {