Property or indexer 'IOpenApiMediaType.Example' cannot be assigned to -- it is read only in OpenAPI.NET 3.0.0

[muhammadzandieh8]

After upgrading a project to .NET 10 and using the built-in Microsoft.AspNetCore.OpenApi package (which seems to support Microsoft.OpenApi 3.0.0 generation), the application fails to start or build correctly. It throws multiple Property or indexer 'IOpenApiMediaType.Example' cannot be assigned to -- it is read only

To Reproduce

1. Create a new ASP.NET Core project targeting .NET 10.
2. Add Microsoft.AspNetCore.OpenApi package.
3. Add Scalar.AspNetCore package.
4. Configure services as follows:

builder.Services.AddOpenApi();
// ... other services
app.MapOpenApi(); 
app.MapScalarApiReference(...);

5. Run the application in Development mode.

Workaround
Downgrading the Microsoft.OpenApi package to version 2.3.9 resolved the runtime error.

Environment:
ASP.NET Core Target: .NET 10.0
Microsoft.AspNetCore.OpenApi version: (auto-included in .NET 10, likely pulling a newer Microsoft.OpenApi version)
Microsoft.OpenApi version: 3.0.0 (causes error), 2.3.9 (workaround, resolves error)
Scalar.AspNetCore version: 2.10.3

[emeryao]

+1 same here

[baywet]

Thank you for using the SDK and for reaching out.

Please have a look at the support policy

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