How to solve the “System.InvalidOperationException: The given header was not found.” exception in Blazor WASM Client

In my Blazor WASM client project, I need to call an API and put the value of "X-Pagination" in its header, unfortunately, when I call this API I get this exception in the browser console:

    WebAssembly.Rendering.WebAssemblyRenderer[100]
      Unhandled exception rendering component: The given header was not found.
   System.InvalidOperationException: The given header was not found.
   at System.Net.Http.Headers.HttpHeaders.GetValues(HeaderDescriptor descriptor)
   at System.Net.Http.Headers.HttpHeaders.GetValues(String name)

My API:

    [HttpPost]
    public async Task<ApiResult<PagedList<ReceiptDto>>> GetAll(Pagable pagable, CancellationToken cancellationToken)
    {
        Guid? userId = User.Identity.GetGuidUserId();

        GetReceiptsQuery query = new(pagable, (Guid)userId);
        var result = await _mediator.Send(query, cancellationToken);

        Response.Headers.Add("X-Pagination", JsonConvert.SerializeObject(result.Data.MetaData));

        return result;
    }

Also I added .AllowAnyHeader() method to the CORS policy API in the startup class:

   services.AddCors(
            options =>
            {
                options.AddDefaultPolicy(builder =>
                {
                    builder.WithOrigins(
                        "https://localhost:44366/",
                        "http://localhost:44366/")
                    .AllowAnyMethod()
                    .AllowAnyHeader()
                    .AllowAnyOrigin();
                });
            })

In my method in wasm client, I call my httpclient and get the values of header :

    public async Task<PagingResponse<ReceiptDto>> GetReceipts(Pagable pagable)
    {
        HttpResponseMessage response = await _client.PostAsJsonAsync("v1/Users/Receipts/GetAll", pagable);

        if (!response.IsSuccessStatusCode)
        {
            throw new ApplicationException(response.Content.ToString());
        }

        var result = await response.Content.ReadAsAsync<ApiResult<List<ReceiptDto>>>();

        if (!result.IsSuccess)
        {
            throw new ApplicationException(result.Message);
        }

        PagingResponse<ReceiptDto> pagingResponse = new()
        {
            Items = result.Data,
            MetaData = JsonSerializer.Deserialize<MetaData>(response.Headers.GetValues("X- Pagination").First(), _options)
        };

        return pagingResponse;
    }

Whereas when I call this API in Postman or Swagger there is no problem :

but as I said at the beginning of my question, when I call this API in the Blazor WASM client, I get the above error.

I encounter an error while calling API, I shared it to solve it.

I finally realized that the API CORS policy should specify what headers are exposed, so I resolved the exception and changed the CORS settings in the API startup class as below:

services.AddCors(
            options =>
            {
                options.AddDefaultPolicy(builder =>
                {
                    builder.WithOrigins(
                        "https://localhost:44366/",
                        "http://localhost:44366/")
                    .AllowAnyMethod()
                    .AllowAnyHeader()
                    .AllowAnyOrigin()
                    .WithExposedHeaders("X-Pagination");  // this line is important
                });
            })