Can't start WireMock.Net server in Xamarin.UITest project (.NET Framework 4.7.2) on MacOS

Describe the bug

I have a Xamarin.UITest project (.NET Framework 4.7.2) where I use WireMock.Net 1.4.1. It’s working fine on Windows but I can’t start the server on MacOS. Using WireMock in a .NET 5 project on MacOS is working. Please have a look at the attached reproduction project. Thanks for your help.

XamarinUITest.zip

WireMock.Exceptions.WireMockException : Service start failed with error: One or more errors occurred. (Could not load type of field 'Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.SocketTransportOptions:<MemoryPoolFactory>k__BackingField' (1) due to: Could not load file or assembly 'System.Memory, Version=4.0.1.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' or one of its dependencies.)
  ----> System.AggregateException : One or more errors occurred. (Could not load type of field 'Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.SocketTransportOptions:<MemoryPoolFactory>k__BackingField' (1) due to: Could not load file or assembly 'System.Memory, Version=4.0.1.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' or one of its dependencies.)
  ----> System.TypeLoadException : Could not load type of field 'Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.SocketTransportOptions:<MemoryPoolFactory>k__BackingField' (1) due to: Could not load file or assembly 'System.Memory, Version=4.0.1.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' or one of its dependencies.
TearDown : System.NullReferenceException : Object reference not set to an instance of an object

Other related info

=== Visual Studio Community 2019 for Mac ===

Version 8.8.4 (build 30) Installation UUID: 94accbf7-86e5-4735-9417-a34560e045b1 GTK+ 2.24.23 (Raleigh theme) Xamarin.Mac 6.18.0.23 (d16-6 / 088c73638)

Package version: 612000113

=== Mono Framework MDK ===

Runtime: Mono 6.12.0.113 (2020-02/4fdfb5b1fd5) (64-bit) Package version: 612000113

=== Roslyn (Language Service) ===

3.8.0-5.20519.18+4c195c3ac1974edcefa76774d7a59a2350ec55fa

=== NuGet ===

Version: 5.8.0.6860

=== .NET Core SDK ===

SDK: /usr/local/share/dotnet/sdk/5.0.101/Sdks SDK Versions: 5.0.101 5.0.100 3.1.404 3.1.402 MSBuild SDKs: /Applications/Visual Studio.app/Contents/Resources/lib/monodevelop/bin/MSBuild/Current/bin/Sdks

=== .NET Core Runtime ===

Runtime: /usr/local/share/dotnet/dotnet Runtime Versions: 5.0.1 5.0.0 3.1.10 3.1.8 2.1.23 2.1.22

=== .NET Core 3.1 SDK ===

SDK: 3.1.404

=== Xamarin.Profiler ===

Version: 1.6.15.68 Location: /Applications/Xamarin Profiler.app/Contents/MacOS/Xamarin Profiler

=== Updater ===

Version: 11

=== Apple Developer Tools ===

Xcode 12.2 (17535) Build 12B45b

=== Xamarin Designer ===

Version: 16.8.0.510 Hash: 44e3f3ce9 Branch: remotes/origin/d16-8 Build date: 2020-12-10 00:06:14 UTC

=== Xamarin.Android ===

Not Installed

=== Microsoft OpenJDK for Mobile ===

Java SDK: Not Found

Android Designer EPL code available here: https://github.com/xamarin/AndroidDesigner.EPL

=== Android SDK Manager ===

Version: 16.8.0.32 Hash: 01a7774 Branch: remotes/origin/d16-8 Build date: 2020-12-10 00:32:24 UTC

=== Android Device Manager ===

Version: 16.8.0.46 Hash: 0a81419 Branch: remotes/origin/d16-8 Build date: 2020-12-10 00:32:44 UTC

=== Xamarin.Mac ===

Xamarin.Mac not installed. Can’t find /Library/Frameworks/Xamarin.Mac.framework/Versions/Current/Version.

=== Xamarin.iOS ===

Version: 14.6.0.15 (Visual Studio Community) Hash: 87a1b18d8 Branch: d16-8 Build date: 2020-11-16 21:39:41-0500

=== Build Information ===

Release ID: 808040030 Git revision: eaa21a8983aa5c4bcf6a665892478b4f3d413418 Build date: 2020-12-10 11:06:12-05 Build branch: release-8.8 Xamarin extensions: eaa21a8983aa5c4bcf6a665892478b4f3d413418

=== Operating System ===

Mac OS X 10.15.7 Darwin 19.6.0 Darwin Kernel Version 19.6.0 Mon Aug 31 22:12:52 PDT 2020 root:xnu-6153.141.2~1/RELEASE_X86_64 x86_64

[xamadev]

@StefH Just tested with version 1.4.38 - it’s working! Thanks a lot for your effort and sorry for the late reply 😃

[StefH]

@xamadev

I’ve added ConfigureAwait(false) to all await calls, so maybe this will solve your issue.

I’m closing this issue now, a new official version will be released in some days.

https://github.com/WireMock-Net/WireMock.Net/pull/704