I have an MVC project that I'm running under mono. It has a reference to System.Web. If I inspect this package using the assembly browser in VS Mac 2019 I can see that it has the class System.Web.Security.AntiXss.AntiXssEncoder. When I insepct the properties of the System.Web package it's path is `/Library/Frameworks/Mono.framework/versions/6.10.0/lib/mono/4.8-api/System.Web.dll.
However when I run this project and request an api route I get a System.TypeLoadException:
Could not resolve type with token 010005dc from typeref (expected class 'System.Web.Security.AntiXss.AntiXssEncoder' in assembly 'System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a')
Thrown from System.ComponentModel.DataAnnotation.ValidationAttribute.IsValid
In the logs when it loads I can see that for some reason the assembly isn't loaded:
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/Microsoft.CSharp/4.0.0.0__b03f5f7f11d50a3a/Microsoft.CSharp.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Data/4.0.0.0__b77a5c561934e089/System.Data.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Web.Services/4.0.0.0__b03f5f7f11d50a3a/System.Web.Services.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Drawing/4.0.0.0__b03f5f7f11d50a3a/System.Drawing.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.EnterpriseServices/4.0.0.0__b03f5f7f11d50a3a/System.EnterpriseServices.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.IdentityModel/4.0.0.0__b77a5c561934e089/System.IdentityModel.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Runtime.Serialization/4.0.0.0__b77a5c561934e089/System.Runtime.Serialization.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Xaml/4.0.0.0__b77a5c561934e089/System.Xaml.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.ServiceModel/4.0.0.0__b77a5c561934e089/System.ServiceModel.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.ServiceModel.Web/4.0.0.0__31bf3856ad364e35/System.ServiceModel.Web.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Web.Extensions/4.0.0.0__31bf3856ad364e35/System.Web.Extensions.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Data.DataSetExtensions/4.0.0.0__b77a5c561934e089/System.Data.DataSetExtensions.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Xml.Linq/4.0.0.0__b77a5c561934e089/System.Xml.Linq.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.ComponentModel.DataAnnotations/4.0.0.0__31bf3856ad364e35/System.ComponentModel.DataAnnotations.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Web.DynamicData/4.0.0.0__31bf3856ad364e35/System.Web.DynamicData.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Data.Linq/4.0.0.0__b77a5c561934e089/System.Data.Linq.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Web.ApplicationServices/4.0.0.0__31bf3856ad364e35/System.Web.ApplicationServices.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.ComponentModel.Composition/4.0.0.0__b77a5c561934e089/System.ComponentModel.Composition.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Data.OracleClient/4.0.0.0__b77a5c561934e089/System.Data.OracleClient.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.IO.Compression.FileSystem/4.0.0.0__b77a5c561934e089/System.IO.Compression.FileSystem.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Management/4.0.0.0__b03f5f7f11d50a3a/System.Management.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Net/4.0.0.0__b03f5f7f11d50a3a/System.Net.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Net.Http.WebRequest/4.0.0.0__b03f5f7f11d50a3a/System.Net.Http.WebRequest.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Numerics/4.0.0.0__b77a5c561934e089/System.Numerics.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Runtime.Caching/4.0.0.0__b03f5f7f11d50a3a/System.Runtime.Caching.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Security/4.0.0.0__b03f5f7f11d50a3a/System.Security.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.ServiceProcess/4.0.0.0__b03f5f7f11d50a3a/System.ServiceProcess.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/System.Transactions/4.0.0.0__b77a5c561934e089/System.Transactions.dll
Loaded assembly: /Library/Frameworks/Mono.framework/Versions/6.10.0/lib/mono/gac/WindowsBase/4.0.0.0__31bf3856ad364e35/WindowsBase.dll
So no sign of System.Web but System.Web.ApplicationServices (which includes a System.Web.Security namespace) is loaded. I can't tell why it wouldn't load the referenced assembly - is this XSP4 deciding which assemblies to load or mono??
Any ideas?