Xamarin 问题初始化 HttpClient

Question

I have an issue with my Android project in Xamarin when running debugging that has just started occurring. It's just about the first thing that happens after InitializeComponent(); in App.xaml.cs . I'm initialising HttpClient as follows:

static readonly HttpClient client = new HttpClient();

but straight away get the following error message:

{System.InvalidProgramException: Invalid IL code in ObjCRuntime.RuntimeOptions:GetHttpMessageHandler (): IL_0000: ret
  at System.Net.Http.HttpClient.CreateDefaultHandler () [0x00000] in <e329308c7a294b1ebc65b0effd900db2>:0 
  at System.Net.Http.HttpClient..ctor () [0x00000] in <e329308c7a294b1ebc65b0effd900db2>:0 
  at [MYAPP].Web.WebClient..cctor () [0x00000] in [MYAPPPATH]\Web\WebClient.cs:20 }

I can't seem to find any help and support out there so any help much appreciated.

Cheers,

Justin

Answer 1

I can confirm with 99% certainty that it's related to the latest updates of Visual Studio 2019 Community (not sure if this is isolated to just Community). I had this exact same issue when I updated from 16.8.x to 16.9.2 and can confirm that it is still present in 16.9.3. I've got a separate laptop with VS 2019 16.7.6 running the same codebase without issue.

Unfortunately it appears that there is no way to rollback VS 2019 Community installs. Hopefully this helps.