Adding Blazor Identity to existing Blazer project fails with a 'null path' exception

Question

Adding Blazor Identity to existing Blazer project fails with a 'null path' exception

kodo65 10

Hi!

I have the following:

.Net SDK 9
Visual Studio Community 2022 v 17.12.3
Windows v10.0.19044
Blazer Server App

When I try to add the Blazor Identity "scaffolding" I get a "There was an error running the selected code generator: 'Value cannot be null. (Parameter 'path'). I can see that some of the EF-framework assemblies and SQLite-engine was installed but nothing else. Is there a solution to this?

Cheers

Anonymous

2024-12-18T12:43:11.2466667+00:00

Hi kodu, per my knowledge, Blazor Server App exists in .Net version before .Net 8, so that .Net 9 doesn't have Blazor Server App, may I know whether Blazor Server here mean Blazor web app which is a new template from .Net 8?
kodo65 10 Reputation points

2024-12-18T13:03:48.1633333+00:00

I'm using Blazor web app - sorry for the confusion.
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2024-12-18T13:43:50.2+00:00

Hi @kodo65,

I tested with Blazor web app, .NET 9 and VS 2022 v17.12.3, but I failed to reproduce this issue.

I show you the steps I followed, kindly let me know if I missed some steps when I tried to reproduce this issue.

Create a .NET 9 Blazor web app, right-click it => Add => New Scaffolded Item... => pick Blazor Identity => click Add, select DbContext class(I added a new data context type), select Database provider(SQL Server) => click Add.

BTW, if you can share us the complete steps to reproduce this issue and check further, it will be very helpful.

I also find a similar thread(state: "Fixed - pending release"): Scaffolding Identity to a web project fails to complete with an error message of "Value cannot be null. (Parameter 'objectToConvert')". Maybe, it's not the same issue, but once the next version of VS 2022 has been released, I think you can also try to update VS 2022 to the latest version.
kodo65 10 Reputation points

2024-12-18T14:07:56.0233333+00:00

I performed exactly the same steps as you with the exception I selected SQLite as I want this to be a bundled solution without relying on the SQLServer (Windows) service. The target system will be run on Linux which means I need to keep the dependencies in Windows components to a minimum. I thought that relying on SQLite would make my solution "more cross platform". Is this correct?
Bruce (SqlWork.com) 77,686 Reputation points Volunteer Moderator

2024-12-18T17:13:07.4633333+00:00

as SQLite is an in process database, it will not work on a webfarm, just single sever.

note: I added Blazor identity with sqlite with no issues:

Microsoft Visual Studio Professional 2022 (64-bit) - Preview Version 17.13.0 Preview 2.0
kodo65 10 Reputation points

2024-12-19T07:48:58.23+00:00

Hi!

In-process is no problem to me as I'll run my app as a docker compose stack on Linux. It's encouraging to hear you didn't experience any problems using the identity scaffolding - unfortunately it doesn't work for me though. Maybe the problem is that I use community version and not a preview...?

Cheers
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2024-12-20T06:16:12.78+00:00

Hi @kodo65 ,

I'm using Community version as well, I also fail to reproduce this issue.

May I confirm, if you added the Blazor Identity to an existing Blazor project or, a newly created Blazor project without modifying anything?

If it's an existing Blazor project, will it work if you delete the bin, obj and the hidden .vs folder in your project/solution folder?

If it's a newly created Blazor project, will it work if you repair VS(VS Installer => More => Repair)?
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2024-12-25T08:20:56.4333333+00:00

@kodo65 ,

Do you still meet this issue? If a repair(VS) doesn't work, perhaps you can try to reinstall the "ASP.NET and web development" workload.

Besides, will it work if you run VS as administrator?
Timo Schneider 0 Reputation points

2025-01-23T12:08:12.58+00:00

I have unfortunately the exact same problem. It concerns an existing application. As mentioned in the other comment, I also deleted the folders. Unfortunately, this did not change the situation. When I look at the output during scaffolding, the error always occurs at… (see image)
AgaveJoe 30,126 Reputation points

2025-01-23T17:52:56.9166667+00:00

When I look at the output during scaffolding, the error always occurs at… (see image)

You did not include the image. If you are getting the same path error and you are using SQLite, make sure you've set the path to the SQLite database in configuration.

https://learn.microsoft.com/en-us/dotnet/standard/data/sqlite/?tabs=net-cli

Also, we have no idea what kind of Blazor application you've got there or even if you are building a Blazor application. Keep in mind, the OP in this post was mistaken as .NET 9 does not have a template for the Blazer Server App.
kodo65 10 Reputation points

2025-01-27T09:16:36.58+00:00
Hi! Sorry missed to include the screen dump:

I have the following:

Microsoft Visual Studio Community 2022 (64-bit) 17.12.3

Blazor web app

Target: .Net 9

Windows 10 Enterprise LTSC. 21H2, 19044.5371

The steps I follow are:

After I click "Add" the tool performs various operations but the end result is the error shown above. However, there's an SQLite configuration added and opening that gives:

Making sure I have a "Data" folder in my project doesn't help! Exactly the same error keeps popping up.

I'm still stranded here :(
kodo65 10 Reputation points

2025-01-28T11:29:35.5666667+00:00

Hi! Sorry for the late reply - I've been away on vacation. I followed your recommendations and removed bin, obj and .vs folders and tried to add the identity scaffolding again but I still get exactly the same result - it fails with the 'Value cannot be null. (Parameter path)'.
kodo65 10 Reputation points

2025-01-28T11:31:13.6166667+00:00

Hi! sorry for the late reply. I followed your recommendation and removed obj, bin and .vs folders but I atill get the same error: 'Value cannot be null (Parameter path)'.
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2025-02-05T12:24:35.6133333+00:00

Hi @kodo65 ,

When you create the project, if you change to use another location(for example, C:\Test) to store the new Blazor web app, will this error disappear?

Also, Visual Studio 2022 version 17.12.4 has been released. Is it possible for you to update VS 2022 from version 17.12.3 to 17.12.4 and check again?

Please click Project => Manage NuGet Packages, search and confirm that the "Microsoft.VisualStudio.Web.CodeGeneration.Design" package has been installed.

Besides, can you confirm if this error appears on a .NET 8.0 Blazor web app?
kodo65 10 Reputation points

2025-02-06T07:21:52.8933333+00:00
Hi!

I'm running:

VS Community 17.12.4

.Net 9

The Packages is installed

Still same error! Sorry.
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2025-02-06T09:57:52.48+00:00

Hi @kodo65 ,

Did you manually set some configurations outside Visual Studio maybe, especially for SQLite, path, .NET...?

I knew that you are using .NET 9, just want to double confirm, the same error also appears on .NET 8.0 Blazor web app, on your side, right?
kodo65 10 Reputation points

2025-02-06T10:02:54.5+00:00

No, haven't touched anything related to SQLite as I've allowed VS handle this completely. SQLite will only be used for managing identities - nothing else. I thought (wrongly?) that it's up to the VS scaffold tooling to handle everything identity related such as establishing the local SQLite db etc...
kodo65 10 Reputation points

2025-02-06T10:13:52.2333333+00:00

On a sidenote - I think I've read this has been confirmed as a bug but that it would be fixed in late January...
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2025-02-06T14:08:26.58+00:00

Hi @kodo65 ,

I think I’ve read this has been confirmed as a bug but that it would be fixed in late January…

If you still remember the corresponding ticket link(Maybe a Developer Community ticket?) it will be helpful for tracking this issue.

I tried multiple times(even test on another newly created VM), but I still fail to reproduce this issue. I also didn’t change or set any other things.

Will resetting VS(close VS => open Developer Command Prompt for VS 2022 => run "devenv /ResetSettings") work?
kodo65 10 Reputation points

2025-05-09T08:58:16.3133333+00:00
Sigh! I'm still struggling with adding this functionality using scaffolding! I'm now up several versions of VS:

VisualStudio.17.Release/17.13.6+35931.197

Microsoft .NET Framework Version 4.8.04084

Could you please provide a complete outline on how to manually add this functionality to my C# Blazor project? It would be very much appreciated!

2 answers

Your answer

Anonymous

2024-12-18T12:43:11.2466667+00:00

Hi kodu, per my knowledge, Blazor Server App exists in .Net version before .Net 8, so that .Net 9 doesn't have Blazor Server App, may I know whether Blazor Server here mean Blazor web app which is a new template from .Net 8?
kodo65 10 Reputation points

2024-12-18T13:03:48.1633333+00:00

I'm using Blazor web app - sorry for the confusion.
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2024-12-18T13:43:50.2+00:00

Hi @kodo65,

I tested with Blazor web app, .NET 9 and VS 2022 v17.12.3, but I failed to reproduce this issue.

I show you the steps I followed, kindly let me know if I missed some steps when I tried to reproduce this issue.

Create a .NET 9 Blazor web app, right-click it => Add => New Scaffolded Item... => pick Blazor Identity => click Add, select DbContext class(I added a new data context type), select Database provider(SQL Server) => click Add.

BTW, if you can share us the complete steps to reproduce this issue and check further, it will be very helpful.

I also find a similar thread(state: "Fixed - pending release"): Scaffolding Identity to a web project fails to complete with an error message of "Value cannot be null. (Parameter 'objectToConvert')". Maybe, it's not the same issue, but once the next version of VS 2022 has been released, I think you can also try to update VS 2022 to the latest version.
kodo65 10 Reputation points

2024-12-18T14:07:56.0233333+00:00

I performed exactly the same steps as you with the exception I selected SQLite as I want this to be a bundled solution without relying on the SQLServer (Windows) service. The target system will be run on Linux which means I need to keep the dependencies in Windows components to a minimum. I thought that relying on SQLite would make my solution "more cross platform". Is this correct?
Bruce (SqlWork.com) 77,686 Reputation points Volunteer Moderator

2024-12-18T17:13:07.4633333+00:00

as SQLite is an in process database, it will not work on a webfarm, just single sever.

note: I added Blazor identity with sqlite with no issues:

Microsoft Visual Studio Professional 2022 (64-bit) - Preview Version 17.13.0 Preview 2.0
kodo65 10 Reputation points

2024-12-19T07:48:58.23+00:00

Hi!

In-process is no problem to me as I'll run my app as a docker compose stack on Linux. It's encouraging to hear you didn't experience any problems using the identity scaffolding - unfortunately it doesn't work for me though. Maybe the problem is that I use community version and not a preview...?

Cheers
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2024-12-20T06:16:12.78+00:00

Hi @kodo65 ,

I'm using Community version as well, I also fail to reproduce this issue.

May I confirm, if you added the Blazor Identity to an existing Blazor project or, a newly created Blazor project without modifying anything?

If it's an existing Blazor project, will it work if you delete the bin, obj and the hidden .vs folder in your project/solution folder?

If it's a newly created Blazor project, will it work if you repair VS(VS Installer => More => Repair)?
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2024-12-25T08:20:56.4333333+00:00

@kodo65 ,

Do you still meet this issue? If a repair(VS) doesn't work, perhaps you can try to reinstall the "ASP.NET and web development" workload.

Besides, will it work if you run VS as administrator?
Timo Schneider 0 Reputation points

2025-01-23T12:08:12.58+00:00

I have unfortunately the exact same problem. It concerns an existing application. As mentioned in the other comment, I also deleted the folders. Unfortunately, this did not change the situation. When I look at the output during scaffolding, the error always occurs at… (see image)
AgaveJoe 30,126 Reputation points

2025-01-23T17:52:56.9166667+00:00

When I look at the output during scaffolding, the error always occurs at… (see image)

You did not include the image. If you are getting the same path error and you are using SQLite, make sure you've set the path to the SQLite database in configuration.

https://learn.microsoft.com/en-us/dotnet/standard/data/sqlite/?tabs=net-cli

Also, we have no idea what kind of Blazor application you've got there or even if you are building a Blazor application. Keep in mind, the OP in this post was mistaken as .NET 9 does not have a template for the Blazer Server App.
kodo65 10 Reputation points

2025-01-27T09:16:36.58+00:00

Hi! Sorry missed to include the screen dump:

I have the following:

Microsoft Visual Studio Community 2022 (64-bit) 17.12.3

Blazor web app

Target: .Net 9

Windows 10 Enterprise LTSC. 21H2, 19044.5371

The steps I follow are:

After I click "Add" the tool performs various operations but the end result is the error shown above. However, there's an SQLite configuration added and opening that gives:

Making sure I have a "Data" folder in my project doesn't help! Exactly the same error keeps popping up.

I'm still stranded here :(
kodo65 10 Reputation points

2025-01-28T11:29:35.5666667+00:00

Hi! Sorry for the late reply - I've been away on vacation. I followed your recommendations and removed bin, obj and .vs folders and tried to add the identity scaffolding again but I still get exactly the same result - it fails with the 'Value cannot be null. (Parameter path)'.
kodo65 10 Reputation points

2025-01-28T11:31:13.6166667+00:00

Hi! sorry for the late reply. I followed your recommendation and removed obj, bin and .vs folders but I atill get the same error: 'Value cannot be null (Parameter path)'.
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2025-02-05T12:24:35.6133333+00:00

Hi @kodo65 ,

When you create the project, if you change to use another location(for example, C:\Test) to store the new Blazor web app, will this error disappear?

Also, Visual Studio 2022 version 17.12.4 has been released. Is it possible for you to update VS 2022 from version 17.12.3 to 17.12.4 and check again?

Please click Project => Manage NuGet Packages, search and confirm that the "Microsoft.VisualStudio.Web.CodeGeneration.Design" package has been installed.

Besides, can you confirm if this error appears on a .NET 8.0 Blazor web app?
kodo65 10 Reputation points

2025-02-06T07:21:52.8933333+00:00

Hi!

I'm running:

VS Community 17.12.4

.Net 9

The Packages is installed

Still same error! Sorry.
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2025-02-06T09:57:52.48+00:00

Hi @kodo65 ,

Did you manually set some configurations outside Visual Studio maybe, especially for SQLite, path, .NET...?

I knew that you are using .NET 9, just want to double confirm, the same error also appears on .NET 8.0 Blazor web app, on your side, right?
kodo65 10 Reputation points

2025-02-06T10:02:54.5+00:00

No, haven't touched anything related to SQLite as I've allowed VS handle this completely. SQLite will only be used for managing identities - nothing else. I thought (wrongly?) that it's up to the VS scaffold tooling to handle everything identity related such as establishing the local SQLite db etc...
kodo65 10 Reputation points

2025-02-06T10:13:52.2333333+00:00

On a sidenote - I think I've read this has been confirmed as a bug but that it would be fixed in late January...
Tianyu Sun-MSFT 34,436 Reputation points Microsoft External Staff

2025-02-06T14:08:26.58+00:00

Hi @kodo65 ,

I think I’ve read this has been confirmed as a bug but that it would be fixed in late January…

If you still remember the corresponding ticket link(Maybe a Developer Community ticket?) it will be helpful for tracking this issue.

I tried multiple times(even test on another newly created VM), but I still fail to reproduce this issue. I also didn’t change or set any other things.

Will resetting VS(close VS => open Developer Command Prompt for VS 2022 => run "devenv /ResetSettings") work?
kodo65 10 Reputation points

2025-05-09T08:58:16.3133333+00:00

Sigh! I'm still struggling with adding this functionality using scaffolding! I'm now up several versions of VS:

VisualStudio.17.Release/17.13.6+35931.197

Microsoft .NET Framework Version 4.8.04084

Could you please provide a complete outline on how to manually add this functionality to my C# Blazor project? It would be very much appreciated!

Answer 1

David Brenchley 20

This is a poor work around, but it worked for me. I built a brand new Blazor net 8.0 project. I added the scaffolding and it worked. I then copied all the new files to my 9 project and the changes to the program.cs file and added the nuget packages. What a pain, but at least I can move forward.

Answer 2

kodo65 10

I appreciate your reply and suggestion, however, I decided to skip the Identity Scaffolding altogether and rolled my own solution instead and have never looked back.

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Adding Blazor Identity to existing Blazer project fails with a 'null path' exception

2 answers

Your answer