Microsoft Graph .NET SDK V5获取用户头像流时类型转换失败问题求助

大家好，我遇到了一个升级Microsoft Graph SDK后的棘手问题，想请各位帮忙排查一下。

我有一个基础的Razor Pages Web应用，通过Microsoft Graph获取用户信息和头像。在使用Microsoft.Graph V4版本时，用ClientSecretCredential认证一切正常，用户信息和头像都能成功获取，还能把头像流转成MemoryStream后显示在页面上。

V4版本项目配置 #

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net9.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <UserSecretsId>aspnet-GraphTest-f0c950ea-9c29-4d6d-af44-7711be58959f</UserSecretsId>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="9.0.2" NoWarn="NU1605" />
    <PackageReference Include="Microsoft.AspNetCore.Authentication.OpenIdConnect" Version="9.0.2" NoWarn="NU1605" />
    <PackageReference Include="Microsoft.Graph" Version="4.54.0" />
    <PackageReference Include="Microsoft.Identity.Web" Version="3.7.1" />
    <PackageReference Include="Microsoft.Identity.Web.UI" Version="3.7.1" />
  </ItemGroup>

</Project>

V4版本后台代码 #

public async Task OnGet()
{
    var options = new ClientSecretCredentialOptions
    {
        AuthorityHost = AzureAuthorityHosts.AzurePublicCloud
    };
    var credentials = new ClientSecretCredential(<tenantid>, <clientid>, <clientsecret>, options);
    var graphServiceClient = new GraphServiceClient(credentials, new string[] { "https://graph.microsoft.com/.default" });

    var user = await graphServiceClient.Users[<userid>].Request().GetAsync();
    ViewData["Name"] = user.DisplayName;

    using var photoStream = await graphServiceClient.Users[<userid>].Photo.Content.Request().GetAsync();
    ViewData["Photo"] = Convert.ToBase64String(((MemoryStream?)photoStream)?.ToArray());
}

但当我把Microsoft.Graph升级到V5.71.0版本，并且按照新语法去掉.Request()后，获取到的头像流类型发生了变化，直接转换会抛出InvalidCastException错误。

V5版本项目配置 #

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net9.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <UserSecretsId>aspnet-GraphTest-f0c950ea-9c29-4d6d-af44-7711be58959f</UserSecretsId>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="9.0.2" NoWarn="NU1605" />
    <PackageReference Include="Microsoft.AspNetCore.Authentication.OpenIdConnect" Version="9.0.2" NoWarn="NU1605" />
    <PackageReference Include="Microsoft.Graph" Version="5.71.0" />
    <PackageReference Include="Microsoft.Identity.Web" Version="3.7.1" />
    <PackageReference Include="Microsoft.Identity.Web.UI" Version="3.7.1" />
  </ItemGroup>

</Project>

V5版本后台代码 #

public async Task OnGet()
{
    var options = new ClientSecretCredentialOptions
    {
        AuthorityHost = AzureAuthorityHosts.AzurePublicCloud
    };
    var credentials = new ClientSecretCredential(<tenantid>, <clientid>, <clientsecret>, options);
    var graphServiceClient = new GraphServiceClient(credentials, new string[] { "https://graph.microsoft.com/.default" });

    var user = await graphServiceClient.Users[<userid>].GetAsync();
    ViewData["Name"] = user.DisplayName;

    using var photoStream = await graphServiceClient.Users[<userid>].Photo.Content.GetAsync();
    ViewData["Photo"] = Convert.ToBase64String(((MemoryStream?)photoStream)?.ToArray());
}

错误发生在这一行：
ViewData["Photo"] = Convert.ToBase64String(((MemoryStream?)photoStream)?.ToArray());

具体错误信息如下：

System.InvalidCastException
HResult=0x80004002
Message=Unable to cast object of type 'Http2ReadStream' to type 'System.IO.MemoryStream'.
Source=System.Private.CoreLib
StackTrace:
at System.Runtime.CompilerServices.CastHelpers.ChkCast_Helper(Void* toTypeHnd, Object obj)
at GraphTest.Pages.IndexModel.d__2.MoveNext() in C:\Users\ojmcf\source\repos\GraphTest\GraphTest\Pages\Index.cshtml.cs:line 43
at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.ExecutorFactory.NonGenericTaskHandlerMethod.d__2.MoveNext()
at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.PageActionInvoker.d__29.MoveNext()
at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.PageActionInvoker.d__31.MoveNext()

我找了一圈没发现有类似问题的讨论，难道只有我遇到这个情况吗？或者有没有大佬已经找到解决办法了？麻烦指点一下！

备注：内容来源于stack exchange，提问作者OjM