Identity scaffolding in .net core 6.0 gives error message "Length cannot be less than zero."

Question

Hello,

I've been trying to scaffold various Identity pages, however I keep getting an error dialog which says "There was an error running the selected code generator: 'Length cannot be less than zero. (Parameter 'length')'". .

In the code generation log, it gives a stack trace:

Finding the generator 'identity'...  
Running the generator 'identity'...  
Length cannot be less than zero. (Parameter 'length')  
   at Microsoft.VisualStudio.Web.CodeGeneration.ActionInvoker.<BuildCommandLine>b__6_0()  
   at Microsoft.Extensions.CommandLineUtils.CommandLineApplication.Execute(String[] args)  
   at Microsoft.VisualStudio.Web.CodeGeneration.ActionInvoker.Execute(String[] args)  
   at Microsoft.VisualStudio.Web.CodeGeneration.CodeGenCommand.Execute(String[] args)  

I'm running version 6.0.7 for the CodeGeneration package.

So is this a bug with the CodeGeneration package? Is there something else I should probably look into for debugging this? How can I get more information for the cause of this error dialog?

Answer 1

Still have the same problem even with latest nuget packages and on .NET 7. Is there any way to get a more detailed error message?

Project 'Portal' has the following package references
   [net7.0]: 
   Top-level Package                                           Requested   Resolved
   > DevExpress.Blazor                                         22.2.5      22.2.5  
   > DevExpress.Blazor.Server.WebAssembly                      22.2.5      22.2.5
   > Microsoft.AspNetCore.Diagnostics                          2.2.0       2.2.0   
   > Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore      7.0.4       7.0.4   
   > Microsoft.AspNetCore.Identity.EntityFrameworkCore         7.0.4       7.0.4   
   > Microsoft.AspNetCore.Identity.UI                          7.0.4       7.0.4   
   > Microsoft.EntityFrameworkCore                             7.0.4       7.0.4   
   > Microsoft.EntityFrameworkCore.Sqlite                      7.0.4       7.0.4   
   > Microsoft.EntityFrameworkCore.SqlServer                   7.0.4       7.0.4   
   > Microsoft.EntityFrameworkCore.Tools                       7.0.4       7.0.4   
   > Microsoft.VisualStudio.Web.CodeGeneration.Design          7.0.5       7.0.5   


Finding the generator 'identity'...
Running the generator 'identity'...
No database provider found. Using 'SqlServer' by default for new DbContext creation!  (Even though I have selected this in menu, it says that there is no provider found)
Length cannot be less than zero. (Parameter 'length')
   at Microsoft.VisualStudio.Web.CodeGeneration.ActionInvoker.<BuildCommandLine>b__6_0()
   at Microsoft.Extensions.CommandLineUtils.CommandLineApplication.Execute(String[] args)
   at Microsoft.VisualStudio.Web.CodeGeneration.ActionInvoker.Execute(String[] args)
   at Microsoft.VisualStudio.Web.CodeGeneration.CodeGenCommand.Execute(String[] args)

Answer 2

I have the same problem with .NET 7, blazor server app with Individual Accounts.

I can however create a new blazor server with individual accounts and scaffold without problems...
I can copy the scaffolded files (login and register) into the original project and I can do changes to the HTML but I can no longer login or register if I do this.

Next time I create a Blazor server or MVC, I'm going to scaffold immediately to avoid this crap...

Answer 3

Marco hit the nail on the head with this for me, I commented out the namespace, program class definition and main method from my program.cs file, confirmed that my project still ran, and I was able to scaffold the razor identity pages I was looking for instead of getting the zero length error.

//namespace ChatBotTemplate
//{
//    public class Program
//    {
//        public static async Task Main(string[] args)
//        {
				var builder = WebApplication.CreateBuilder(args);
				//More code
				var app = builder.Build();
//        }
//	  }
//}

Cheers Marco.