Error when running blazor wasm in .Net 5.0

[YairHalberstadt]

I'm not sure if blazor wasm is currently supported in .Net 5.0 preview 4, in which case feel free to close this, but thought I would try it out, as I need some types which are not available in .Net Standard.

When I converted my existing .Net STandard 2.1 blazor application to .Net 5.0 preview 4, it built fine, but when I ran it, I got this error:

blazor.webassembly.js:1 System.BadImageFormatException: Could not resolve field token 0x0400000c, 
due to: Could not set up parent class, due to: Could not set up parent class, 
due to: Could not set up parent class, due to: Could not load type of field 'Microsoft.JSInterop.JSRuntime:_cancellationRegistrations' (4) 
due to: Could not resolve type with token 0100001c from typeref (expected class 'System.Threading.CancellationTokenRegistration' in assembly 'System.Runtime, Version=4.2.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a')
assembly:System.Runtime, Version=4.2.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a type:System.Threading.CancellationTokenRegistration member:(null)
assembly:Microsoft.JSInterop.dll type:JSRuntime member:(null)
assembly:Microsoft.JSInterop.dll type:JSInProcessRuntime member:(null)
assembly:Microsoft.JSInterop.WebAssembly.dll type:WebAssemblyJSRuntime member:(null)
assembly:Microsoft.AspNetCore.Components.WebAssembly.dll type:DefaultWebAssemblyJSRuntime member:(null)

[javiercn]

@YairHalberstadt thanks for contacting us.

Blazor WebAssembly is not currently supported in .NET 5.0. We are working on adding support now that the 3.2 release is out.