[dotnet-sdk-9.0.100-preview.5.24281.15] Fail to build the app after retargeted to .NET 9.0 with error “System.ArgumentException: An item with the same key has already been added.”

[Junjun-zhao]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When retarget the 3rd party application to net9.0 with the latest .NET 9 build, it failed to build with error "The "DefineStaticWebAssetEndpoints" task failed unexpectedly. System.ArgumentException: An item with the same key has already been added.".

Application Name: NSK, Blazorise, OpenMu
OS： Windows 10 21H2
CPU: X64
.NET Build Number: dotnet-sdk-9.0.100-preview.5.24281.15
App & Source Location checking at: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2069020
Github Link:
https://github.com/andysal/NSK
https://github.com/Megabit/Blazorise
https://github.com/MUnique/OpenMU

Verify Scenarios:
1). Windows 10 21H2 AMD64 + dotnet-sdk-8.0.301: Pass
2). Windows 10 21H2 AMD64 + dotnet-sdk-9.0.100-preview.4.24267.66: Pass
3). Windows 10 21H2 AMD64 + dotnet-sdk-9.0.100-preview.5.24277.8: Fail
4). Windows 10 21H2 AMD64 + dotnet-sdk-9.0.100-preview.5.24281.15: Fail

Expected Behavior

build successfully.

Steps To Reproduce

Minimal Repro steps (Demo attached): BlazorAppDemo (1).zip

1. Create a net7.0 blazor server project named BlazorApp1.
2. Create another net7.0 blazor server project named BlazorApp2 in the same solution.
3. BlazorApp1 add project reference with BlazorApp2.
4. Retarget BlazorApp1 to net9.0.
5. Build BlazorApp1.

Exceptions (if any)

Show error MSB4018:

The "DefineStaticWebAssetEndpoints" task failed unexpectedly.
System.ArgumentException: An item with the same key has already been added.
at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
at Microsoft.AspNetCore.StaticWebAssets.Tasks.DefineStaticWebAssetEndpoints.Execute()
at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()

.NET Version

dotnet-sdk-9.0.100-preview.5.24281.15

Anything else?

Dotnet Info:
.NET SDK:
 Version:           9.0.100-preview.5.24281.15
 Commit:            b6a8831c57
 Workload version:  9.0.100-manifests.6fd52e3d
 MSBuild version:   17.11.0-preview-24279-02+b963c24ef

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19045
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Program Files\dotnet\sdk\9.0.100-preview.5.24281.15\

Host:
  Version:      9.0.0-preview.5.24280.5
  Architecture: x64
  Commit:       de6897b3b7

.NET SDKs installed:
  9.0.100-preview.5.24281.15 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 9.0.0-preview.5.24280.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 9.0.0-preview.5.24280.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 9.0.0-preview.5.24280.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

@dotnet-actwx-bot @dotnet/compat

[javiercn]

@Junjun-zhao thanks for contacting us.

What's happening here is that site.css and site.css in both projects have the same content, and that results in the file name we choose for compression ends up being the same.

[Junjun-zhao]

Thanks @javiercn for looking into this issue so quickly. This issue has been added to 9.0-preview7 milestone, so it is not a blocker for .NET 9 Preview5, is it right?

[javiercn]

No

[dewelloper]

No ?

[javiercn]

@Junjun-zhao this was fixed in preview6, please give it a try with a newer SDK version

[Junjun-zhao]

@javiercn Verified this issue with dotnet-sdk-9.0.100-preview.7.24379.15, it has been fixed.

[robertmclaws]

I don't believe this has been fixed in Preview 7. I am now experiencing it in my projects. It happens when the .NET 9.0 SDK tries to build a .NET 8.0 WebAssembly project.

[robertmclaws]

@javiercn It looks to me like this line:

var staticWebAssets = CandidateAssets.Select(StaticWebAsset.FromTaskItem).ToDictionary(a => a.Identity);

needs to be changed to

var staticWebAssets = CandidateAssets.Select(StaticWebAsset.FromTaskItem).DistinctBy(a => a.Identity).ToDictionary(a => a.Identity);

But I could be wrong.

[Junjun-zhao]

@robertmclaws We verified the affected three apps in our lab with .NET 9 Preview 7 build 9.0.100-preview.7.24407.12 , the issue does not repro that all of them could be built and published successfully. But they are not blazor web assembly apps. Are you using the .NET 9 P7 build 9.0.100-preview.7.24407.12? Do you have a demo or github project link?

[robertmclaws]

Output from dotnet --info:

.NET SDK:
 Version:           9.0.100-preview.7.24407.12
 Commit:            d672b8a045
 Workload version:  9.0.100-manifests.baed1e37
 MSBuild version:   17.12.0-preview-24374-02+48e81c6f1

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.27686
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Program Files\dotnet\sdk\9.0.100-preview.7.24407.12\

.NET workloads installed:
Configured to use loose manifests when installing new manifests.
 [aspire]
   Installation Source: SDK 9.0.100-preview.7, VS 17.11.35208.52
   Manifest Version:    8.1.0/8.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.aspire\8.1.0\WorkloadManifest.json
   Install Type:        FileBased

 [wasm-tools]
   Installation Source: SDK 9.0.100-preview.7, VS 17.11.35208.52
   Manifest Version:    9.0.0-preview.7.24405.7/9.0.100-preview.7
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\9.0.100-preview.7\microsoft.net.workload.mono.toolchain.current\9.0.0-preview.7.24405.7\WorkloadManifest.json
   Install Type:              Msi


Host:
  Version:      9.0.0-preview.7.24405.7
  Architecture: x64
  Commit:       static

.NET SDKs installed:
  6.0.417 [C:\Program Files\dotnet\sdk]
  7.0.407 [C:\Program Files\dotnet\sdk]
  8.0.203 [C:\Program Files\dotnet\sdk]
  8.0.301 [C:\Program Files\dotnet\sdk]
  8.0.400 [C:\Program Files\dotnet\sdk]
  9.0.100-preview.7.24407.12 [C:\Program Files\dotnet\sdk]

Luckily the solution I was trying to upgrade was OSS. If you pull down this codebase and try to build in on VS 17.12 Preview 1, you will run into the issue when you get to building CloudNimble.BlazorEssentials.TestApp.

But they are not blazor web assembly apps.

Can I ask why the team did not test these changes will ALL permutations of the new .targets file? WebAssembly is not an edge case, not testing this with those libraries seems like a MASSIVE oversight.

[Basyras]

Same here. After updating my VS preview version to 9.0.100-preview.7.24407.12 [C:\Program Files\dotnet\sdk], starting to see the The "DefineStaticWebAssetEndpoints" task failed unexpectedly. when building Blazor Wasm project,

[Junjun-zhao]

Thanks @robertmclaws.

Hi @javiercn It prompts the same error message regarding "DefineStaticWebAssetEndpoints" task, but the stack trace is a little different from this issue. We have designed a minimal demo and file a new issue #57423 for tracking. Could you please take a look at? Thanks.