Unable to send large byte array from the server to the client in Blazor

[sathiyaseelanksf3503]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

An exception occurred with the message 'A task was canceled' while attempting to send a PDF file's byte array from the server to the client in Blazor, after retrieving the file from the root folder.

Expected Behavior

Expected behavior get the file byte array in the client and open the byte array has PDF.

Steps To Reproduce

Below provided the replication steps with the Sample.

• Run the sample.
• Click the "Load Large PDF" button.
• Exception occurred.

Exceptions (if any)

.NET Version

Dotnet 8.0

Anything else?

The functionality works correctly in .NET 9.0, but the issue occurs specifically in .NET 8.0.

Code Snippet

Server-side code

@page "/"
@inject IJSRuntime JS
@inject IWebHostEnvironment Env

<button @onclick="LoadLargeFile">Load Large Pdf</button>

@code {
    private DotNetObjectReference<Home>? objRef;

    public void LoadLargeFile()
    {
        LoadPdf("200MB_File.pdf");
    }

    public async void LoadPdf(string fileName)
    {
        var filePath = Path.Combine(Env.WebRootPath, "files", fileName);
        byte[]? fileBytes = await File.ReadAllBytesAsync(filePath);
        await JS.InvokeVoidAsync("pdfInterop.receivePdfBytes", fileBytes, objRef);
        fileBytes = null;
    }
}

Client-side code

window.pdfInterop = {
    receivePdfBytes: function (byteArray, dotNetRef) {
        // Create a Blob and open as PDF
        const blob = new Blob([byteArray], { type: 'application/pdf' });
        const url = URL.createObjectURL(blob);
        window.open(url, '_blank');
    }
};

[willdean]

There are (small) default size limits on the SignalR connections used by Blazor Server.

You might want to look at adjusting HubOptions.MaximumReceiveMessageSize

There's a bit at the bottom of this page about the problem: https://learn.microsoft.com/en-us/aspnet/core/blazor/javascript-interoperability/?view=aspnetcore-9.0