diff --git a/csharp/App/Backend/Controllers/Controller.cs b/csharp/App/Backend/Controllers/Controller.cs
index 2351d5e92..39aa52ccb 100644
--- a/csharp/App/Backend/Controllers/Controller.cs
+++ b/csharp/App/Backend/Controllers/Controller.cs
@@ -1,5 +1,6 @@
 using System.Net;
 using System.Text;
+using System.Web.Http;
 using InnovEnergy.App.Backend.Database;
 using InnovEnergy.App.Backend.Model;
 using InnovEnergy.App.Backend.Model.Relations;
@@ -10,39 +11,38 @@ using HttpContextAccessor = Microsoft.AspNetCore.Http.HttpContextAccessor;
 namespace InnovEnergy.App.Backend.Controllers;
 
 [ApiController]
-[Route("api/")]
+[Microsoft.AspNetCore.Mvc.Route("api/")]
 public class Controller  
 {
     [Returns<String>]
     [Returns(HttpStatusCode.Unauthorized)]
     [Returns(HttpStatusCode.BadRequest)]
-    [HttpPost($"{nameof(Login)}")]
+    [Microsoft.AspNetCore.Mvc.HttpPost($"{nameof(Login)}")]
     public Object Login(Credentials credentials)
     {
         if (String.IsNullOrWhiteSpace(credentials.Username) ||
             String.IsNullOrWhiteSpace(credentials.Password))
-            return new HttpResponseMessage(HttpStatusCode.BadRequest);
-        
+            return new HttpResponseException(HttpStatusCode.BadRequest);
+
         using var db = Db.Connect();
         var user = db.GetUserByEmail(credentials.Username);
-        
-        if (user is null)
-            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
 
-        #if !DEBUG
+
+        if (user is null)
+            return new HttpResponseException(HttpStatusCode.BadRequest);
+
         if (!VerifyPassword(credentials.Password, user))
-             return new HttpResponseMessage(HttpStatusCode.Unauthorized);   
-        #endif
-        
+            return new HttpResponseException(HttpStatusCode.Unauthorized);
+
         var ses = new Session(user);
         db.NewSession(ses);
-        return ses.Token;
+        return new {ses.Token, user.Language};
     }
 
 
     [Returns(HttpStatusCode.OK)]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpPost($"{nameof(Logout)}")]
+    [Microsoft.AspNetCore.Mvc.HttpPost($"{nameof(Logout)}")]
     public Object Logout()
     {
         var caller = GetCaller();
@@ -57,7 +57,7 @@ public class Controller
     
     [Returns(HttpStatusCode.OK)]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpGet($"{nameof(GetInstallationS3Key)}")]
+    [Microsoft.AspNetCore.Mvc.HttpGet($"{nameof(GetInstallationS3Key)}")]
     public Object GetInstallationS3Key(Int64 installationId)
     {
         var caller = GetCaller();
@@ -82,7 +82,7 @@ public class Controller
 
     [Returns<User>]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpGet($"{nameof(GetUserById)}")]
+    [Microsoft.AspNetCore.Mvc.HttpGet($"{nameof(GetUserById)}")]
     public Object GetUserById(Int64 id)
     {
         var caller = GetCaller();
@@ -101,7 +101,7 @@ public class Controller
     
     [Returns<Installation>]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpGet($"{nameof(GetInstallationById)}")]
+    [Microsoft.AspNetCore.Mvc.HttpGet($"{nameof(GetInstallationById)}")]
     public Object GetInstallationById(Int64 id)
     {
         var caller = GetCaller();
@@ -120,7 +120,7 @@ public class Controller
     
     [Returns<Folder>]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpGet($"{nameof(GetFolderById)}")]
+    [Microsoft.AspNetCore.Mvc.HttpGet($"{nameof(GetFolderById)}")]
     public Object GetFolderById(Int64 id)
     {
         var caller = GetCaller();
@@ -139,7 +139,7 @@ public class Controller
     
     [Returns<Installation[]>]  // assuming swagger knows about arrays but not lists (JSON) 
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpGet($"{nameof(GetAllInstallations)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpGet($"{nameof(GetAllInstallations)}/")]
     public Object GetAllInstallations()
     {
         var caller = GetCaller();
@@ -156,7 +156,7 @@ public class Controller
     
     [Returns<Folder[]>]  // assuming swagger knows about arrays but not lists (JSON)
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpGet($"{nameof(GetAllFolders)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpGet($"{nameof(GetAllFolders)}/")]
     public Object GetAllFolders()
     {
         var caller = GetCaller();
@@ -171,7 +171,7 @@ public class Controller
     
     [Returns<TreeNode[]>]  // assuming swagger knows about arrays but not lists (JSON)
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpGet($"{nameof(GetTree)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpGet($"{nameof(GetTree)}/")]
     public Object GetTree()
     {
         var caller = GetCaller();
@@ -193,7 +193,7 @@ public class Controller
 
     [Returns<TreeNode[]>]  // assuming swagger knows about arrays but not lists (JSON)
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpGet($"{nameof(GetAllFoldersAndInstallations)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpGet($"{nameof(GetAllFoldersAndInstallations)}/")]
     public Object GetAllFoldersAndInstallations()
     {
         var caller = GetCaller();
@@ -229,7 +229,7 @@ public class Controller
     
     [Returns(HttpStatusCode.OK)]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpPost($"{nameof(CreateUser)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpPost($"{nameof(CreateUser)}/")]
     public Object CreateUser(User newUser)
     {
         var caller = GetCaller();
@@ -244,7 +244,7 @@ public class Controller
     
     [Returns(HttpStatusCode.OK)]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpPost($"{nameof(CreateInstallation)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpPost($"{nameof(CreateInstallation)}/")]
     public Object CreateInstallation(Installation installation)
     {
         var caller = GetCaller();
@@ -260,7 +260,7 @@ public class Controller
     
     [Returns(HttpStatusCode.OK)]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpPost($"{nameof(CreateFolder)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpPost($"{nameof(CreateFolder)}/")]
     public Object CreateFolder(Folder folder)
     {
         var caller = GetCaller();
@@ -275,7 +275,7 @@ public class Controller
 
     [Returns(HttpStatusCode.OK)]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpPut($"{nameof(UpdateUser)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpPut($"{nameof(UpdateUser)}/")]
     public Object UpdateUser(User updatedUser)
     {
         var caller = GetCaller();
@@ -289,7 +289,7 @@ public class Controller
     
     [Returns(HttpStatusCode.OK)]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpPut($"{nameof(UpdateInstallation)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpPut($"{nameof(UpdateInstallation)}/")]
     public Object UpdateInstallation(Installation installation)
     {
         var caller = GetCaller();
@@ -321,7 +321,7 @@ public class Controller
     
     [Returns(HttpStatusCode.OK)]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpPut($"{nameof(UpdateFolder)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpPut($"{nameof(UpdateFolder)}/")]
     public Object UpdateFolder(Folder folder)
     {
         var caller = GetCaller();
@@ -353,7 +353,7 @@ public class Controller
     
     [Returns(HttpStatusCode.OK)]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpDelete($"{nameof(DeleteUser)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpDelete($"{nameof(DeleteUser)}/")]
     public Object DeleteUser(Int64 userId)
     {
         var caller = GetCaller();
@@ -375,7 +375,7 @@ public class Controller
     
     [Returns(HttpStatusCode.OK)]
     [Returns(HttpStatusCode.Unauthorized)]
-    [HttpDelete($"{nameof(DeleteInstallation)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpDelete($"{nameof(DeleteInstallation)}/")]
     public Object DeleteInstallation(Int64 installationId)
     {
         var caller = GetCaller();
@@ -398,7 +398,7 @@ public class Controller
     
     [ProducesResponseType(200)]
     [ProducesResponseType(401)]
-    [HttpDelete($"{nameof(DeleteFolder)}/")]
+    [Microsoft.AspNetCore.Mvc.HttpDelete($"{nameof(DeleteFolder)}/")]
     public Object DeleteFolder(Int64 folderId)
     {
         var caller = GetCaller();
diff --git a/csharp/App/Backend/Model/User.cs b/csharp/App/Backend/Model/User.cs
index a6fd45c61..6e4e248ad 100644
--- a/csharp/App/Backend/Model/User.cs
+++ b/csharp/App/Backend/Model/User.cs
@@ -8,6 +8,7 @@ public class User : TreeNode
     public String  Email          { get; set; } = null!;
     public Boolean HasWriteAccess { get; set; } = false;
     public String  Salt           { get; set; } = null!;
+    public String  Language       { get; set; } = null!;
     public String  Password       { get; set; } = null!;
     
     // TODO: must reset pwd
diff --git a/csharp/App/Backend/db.sqlite b/csharp/App/Backend/db.sqlite
index 6b0d2d492..1d3664c4c 100644
Binary files a/csharp/App/Backend/db.sqlite and b/csharp/App/Backend/db.sqlite differ