Salve a tutti, in fase di compilazione ottengo questo errore:

Errore di compilazione
Descrizione: Errore durante la compilazione di una risorsa necessaria per soddisfare la richiesta. Rivedere i dettagli relativi all'errore e modificare in modo appropriato il codice sorgente.

Messaggio di errore del compilatore: BC2014: il valore 'default' non è valido per l'opzione 'langversion'

Errore nel codice sorgente:


[Nessuna riga di codice sorgente corrispondente]

File di origine: vbc : Command line Riga: 0


Mostra dettagli dell'output del compilatore:

C:\Program Files (x86)\IIS Express> "C:\Windows\Microsoft.NET\Framework\v4.0.30319\vbc.exe" /t:library /utf8output /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Web.Entity\v4.0_4.0.0.0__b77a5c561934e089\System.Web.Entity.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_32\System.EnterpriseServices\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.EnterpriseServices.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.ComponentModel.DataAnnotations\v4.0_4.0.0.0__31bf3856ad364e35\System.ComponentModel.DataAnnotations.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Configuration\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Configuration.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Drawing\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Drawing.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel.Web\v4.0_4.0.0.0__31bf3856ad364e35\System.ServiceModel.Web.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_32\System.Web\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Web.dll" /R:"C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\vs\3fb3436f\55eeecb6\assembly\dl3\d52044f5\b3f184f3_6158d701\NewSitoReprocart.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Web.Extensions\v4.0_4.0.0.0__31bf3856ad364e35\System.Web.Extensions.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_32\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\Microsoft.CSharp\v4.0_4.0.0.0__b03f5f7f11d50a3a\Microsoft.CSharp.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Web.ApplicationServices\v4.0_4.0.0.0__31bf3856ad364e35\System.Web.ApplicationServices.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel.Activation\v4.0_4.0.0.0__31bf3856ad364e35\System.ServiceModel.Activation.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Runtime.Serialization\v4.0_4.0.0.0__b77a5c561934e089\System.Runtime.Serialization.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Web.Services\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Web.Services.dll" /R:"C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\vs\3fb3436f\55eeecb6\assembly\dl3\aa5bd7fc\0091ab3f_2245d401\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel.Activities\v4.0_4.0.0.0__31bf3856ad364e35\System.ServiceModel.Activities.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Data.DataSetExtensions\v4.0_4.0.0.0__b77a5c561934e089\System.Data.DataSetExtensions.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\Microsoft.VisualStudio.Web.PageInspector.Loader\v4.0_1.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualStudio.Web.PageInspector.Loader.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Xml.Linq\v4.0_4.0.0.0__b77a5c561934e089\System.Xml.Linq.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.WorkflowServices\v4.0_4.0.0.0__31bf3856ad364e35\System.WorkflowServices.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Activities\v4.0_4.0.0.0__31bf3856ad364e35\System.Activities.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.IdentityModel\v4.0_4.0.0.0__b77a5c561934e089\System.IdentityModel.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Core\v4.0_4.0.0.0__b77a5c561934e089\System.Core.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel\v4.0_4.0.0.0__b77a5c561934e089\System.ServiceModel.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Web.DynamicData\v4.0_4.0.0.0__31bf3856ad364e35\System.Web.DynamicData.dll" /R:"C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Xml\v4.0_4.0.0.0__b77a5c561934e089\System.Xml.dll" /out:"C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\vs\3fb3436f\55eeecb6\App_Web_masterpage.master.cdcab7d2.xf2hnikn.dll" /D:DEBUG=1 /debug+ /nowarn:41008,40000,40008 /define:_MYTYPE=\"Web\" /imports:Microsoft.VisualBasic,System,System.Collections,System.Collections.Generic,System.Collections.Specialized,System.ComponentModel.DataAnnotations,System.Configuration,System.Linq,System.Text,System.Text.RegularExpressions,System.Web,System.Web.Caching,System.Web.DynamicData,System.Web.SessionState,System.Web.Security,System.Web.Profile,System.Web.UI,System.Web.UI.WebControls,System.Web.UI.WebControls.WebParts,System.Web.UI.HtmlControls,System.Xml.Linq /langversion:default /nowarn:41008 /define:_MYTYPE=\"Web\" /optionInfer+ /warnaserror- /optionInfer+ "C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\vs\3fb3436f\55eeecb6\App_Web_masterpage.master.cdcab7d2.xf2hnikn.0.vb" "C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\vs\3fb3436f\55eeecb6\App_Web_masterpage.master.cdcab7d2.xf2hnikn.1.vb"


Microsoft (R) Visual Basic Compiler version 14.8.4084
for Visual Basic 2012
Copyright (c) Microsoft Corporation. All rights reserved.

This compiler is provided as part of the Microsoft (R) .NET Framework, but only supports language versions up to Visual Basic 2012, which is no longer the latest version. For compilers that support newer versions of the Visual Basic programming language, see http://go.microsoft.com/fwlink/?LinkID=533241

vbc : Command line error BC2014 : il valore 'default' non è valido per l'opzione 'langversion'


Il Framework installato è la versione 4.8

Grazie a tutti anticipatamente per l'aiuto