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Fallback file endpoints

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The ConsumesAttribute attribute allows controller actions to specify their supported content types. Starting in .NET 6, if a fallback file endpoint was configured, it could match routes that were discarded because the request had a different content type than what was specified in an action's ConsumesAttribute. The .NET 6 behavior was an undesirable change from the .NET 5 behavior. This breaking change partially addresses the issue by making fallback file endpoints only match GET and HEAD requests.

Version introduced

ASP.NET Core 7.0 RC 2

Previous behavior

Endpoints configured with StaticFilesEndpointRouteBuilderExtensions.MapFallbackToFile matched requests made with any request method.

New behavior

Endpoints configured with StaticFilesEndpointRouteBuilderExtensions.MapFallbackToFile only match HEAD and GET requests.

Type of breaking change

This change can affect binary compatibility.

Reason for change

This change partially reverts a larger breaking change accidentally introduced in .NET 6. Since it's highly unusual to expect a fallback file response when making a request with a method other than HEAD or GET, the impact of this breaking change should be minimal.

If you want fallback file endpoints to match requests with methods other than HEAD or GET, you can specify additional HTTP request methods using WithMetadata(). For example:

endpoints.MapFallbackToFile("index.html")
    .WithMetadata(new HttpMethodMetadata(new[] { /* List supported methods here */ }));

Affected APIs