Error: Circuit has been shut down due to error. on downloading file from Blazor Server

I created a webapp using Blazor Server. Part of the webapp is a file download as follows:

// called on button click, initiates the download
private async Task OnDownloadRequest(FileEntry file)
{
    NavManager.NavigateTo($"/download/{file.Id}", true);
}

// MVC controller
public class DownloadController
{
    [HttpGet("~/download/{downloadId}")]
    public async Task<IActionResult> Download([FromServices] MyContext dbContext, long downloadId, CancellationToken cancel)
    {
        File file = await dbContext.Files.FindAsync(downloadId);
        Stream stream = new MemoryStream(file.Content); 

        var result = new FileStreamResult(stream, "application/octet-stream")
        {
            FileDownloadName = file.Name,
            LastModified = file.LastModified
        };

        return result;
    }
}

// Startup.cs Configure method contains:
app.UseEndpoints(endpoints =>
{
    endpoints.MapBlazorHub();
    endpoints.MapControllerRoute("mvc", "{controller}/{action}");
    endpoints.MapFallbackToPage("/_Host");
});

Actually the download of the file works fine, but at the same time Blazor crashes with:

blazor.server.js:19 [2020-09-05T11:33:02.200Z] Error: Circuit has been shut down due to error.
e.log @ blazor.server.js:19
blazor.server.js:1 [2020-09-05T11:33:02.202Z] Information: Connection disconnected.

Anyone knows why blazor crashes in this case and how to fix it?