.NET Core 8 - Download file, client does not have the Content-Disposition Header

I have a simple File Upload / Download app with the client in Blazor and the Server as an ASP.NET Core 8 Web API. I set the Content-Disposition in the API with this code:

[HttpGet("{fileName}")]public async Task<IActionResult> Get(string fileName){     var memoryStream = new MemoryStream();     try     {         if (string.IsNullOrWhiteSpace(fileName))         {             throw new ApplicationException("FileName is required as a path parameter.");         }         string fullPathName = Path.Combine(_settings.UploadRootFolder!, fileName);         if (!System.IO.File.Exists(fullPathName))         {             throw new ApplicationException($"{fileName} does not exist in {_settings.UploadRootFolder}.");         }         var fi = new FileInfo(fullPathName);         var contentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment")         {             //ModificationDate = fi.LastAccessTimeUtc,             FileName = fileName,             FileNameStar = fileName,             Size = fi.Length,             //CreationDate = fi.CreationTimeUtc,             //DispositionType = "attachment",             //ReadDate = DateTime.UtcNow,         };         var mem = System.Diagnostics.Process.GetCurrentProcess().WorkingSet64;         var memKB = mem / 1024;            Response.Headers.ContentDisposition = contentDisposition.ToString();         _logger.LogInformation($"Attempting to download {fileName} from {_settings.UploadRootFolder} using {memKB.ToString("n0")} KB memory.");         using (var fileStream = new FileStream(fullPathName, FileMode.Open, FileAccess.Read))         {             await fileStream.CopyToAsync(memoryStream, 64 * 1024);             memoryStream.Position = 0;             return new FileStreamResult(memoryStream, MimeTypes.GetMimeType(fileName));         }     }     catch (Exception ex)     {         _logger.LogError(ex, "Exception trying to download a file");         return BadRequest();     }}

In my client (Blazor), I invoke the download with this code:

private async Task btnDownload_Clicked(string fileName){     if (!string.IsNullOrWhiteSpace(fileName))     {         try         {                             var response = await _apiClient.GetAsync($"/api/FileDownload/{fileName}");             response.EnsureSuccessStatusCode();             //             // Even though the API successfully set the ContentDisposition header              // (verified using debugger) it is null here on the client.             //             // var serverFileName = response.Content.Headers.ContentDisposition.FileName;              var serverFileName =  fileName;                             using (var stremRef = new DotNetStreamReference(stream: response.Content.ReadAsStream()))             {                 await JS.InvokeVoidAsync("downloadFileFromStream", serverFileName, stremRef);             }         }         catch (Exception ex)         {             JS.InvokeVoidAsync("alert", ex.Message);             throw;         }     }}

I get a NullReferenceException because the fName is NULL because the Headers.ContentDisposition is NULL.

I should be able to set serverFileName to the name found in Content-Disposition, but it is always NULL.

When I comment out the line to get the filename from the header and just use the argument I sent in the path, the download is successful, however, I need to be using Content-Disposition.

Any help is appreciated, my API is running on https://localhost:7283 and my client is running on https://localhost:7203 so they are NOT a Blazor app downloaded from the Client/Server model that VS recommends as a template (separate Client and Server sites seems more real-world).

Thanks for any assistance!