System.ArgumentException: An item with the same key has already been added. Key: Cross-Origin-Embedder-Policy

[Jasonlhy]

Describe the bug I want to add two headers so that SharedArrayBuffer can be enabled on the JavaScript side so I set up the .netconfig file as follow:

[serve]
    header = Cross-Origin-Embedder-Policy: require-corp
    header = Cross-Origin-Opener-Policy: same-origin

Sometimes it works, sometimes it doesn't work. Error message: System.ArgumentException: An item with the same key has already been added. Key: Cross-Origin-Embedder-Policy

To Reproduce Steps to reproduce the behavior: Environment: Ubuntu 22

1. Run dotnet serve
2. Or run dotnet serve --headers "Cross-Origin-Embedder-Policy:require-corp" --headers "Cross-Origin-Opener-Policy:same-origin"

You can just test this repo in Github codespace: https://github.com/Jasonlhy/emcc-playground

Environment Windows 11

1. Run dotnet serve is fine without facing any issues, it can also add the two headers
2. Run dotnet serve --headers "Cross-Origin-Embedder-Policy:require-corp" --headers "Cross-Origin-Opener-Policy:same-origin" will face the same issue

Workaround Run dotnet serve .netconfig

Expected behavior Two headers should be added successfully without facing any error

Screenshots

[natemcmaster]

None of the code in this project adds this header. Have you checked if there is something happening automatically in the ASP.NET Core framework itself? I did a quick search and see a few issues mentioning this header, https://github.com/dotnet/aspnetcore/search?q=Cross-Origin-Embedder-Policy&type=issues.

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[github-actions[bot]]

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