Build error - MSB4018: The "DefineStaticWebAssets" task failed unexpectedly.

_This issue has been moved from [a ticket on Developer Community](https://developercommunity.visualstudio.com/t/Build-error---MSB4018:-The-DefineStatic/10954694)._

---
[severity:It's more difficult to complete my work]
I have cloned a repository which I have not worked on before which contains a solution with multiple projects.

When I try to build the solution I get the same build error which effects 4 projects (Other projects are not effected)...

>MSB4018 - The "DefineStaticWebAssets" task failed unexpectedly.
System.ArgumentException: An item with the same key has already been added.

**System information:**
_IDE and version:_ Visual Studio Community 2022 version: 17.14.13 (August 2025)
_SDK version:_ 9.0.304

**Steps I have taken to try and fix the problem myself:**
- Cleared NuGet local packages, deleted existing bin and obj directories in all projects and Re-built the solution.
- Uninstalled and reinstalled Visual Studio
- Uninstalled and reinstalled Visual Studio using the .vsconfig from someone who has no issues building the project.
- Deleted the solution completely and cloned a fresh copy.
- Studied the Build Log to ascertain what the actual error is.

All of these steps have made no difference and I keep getting the same build error.

I have submitted the Build Log so you can see in more detail where the problems lie.

---
### Original Comments

#### Feedback Bot on 8/22/2025, 07:46 AM:

We have directed your feedback to the appropriate engineering team for further evaluation. The team will review the feedback and notify you about the next steps.