升级到VS 2010和.NET 4.0后LINQ停止工作

Question

I have started using Visual Studio 2010 recently. I have upgraded my solution from old 2008. After this I have tried to run my project, which is very simple database search engine using linq commands and it worked. Then I have switched to .NET 4 and since then I am dead in the water. Any linq query does not execute, nor any exception is thrown. When I pause while the linq command is being executed, it freezes on DataContext.GetTable() method. All I could come up with were some compatibility issues, but I could not figure out what exactly the problem is.

My Linq command is typical "select *":

var query = from mateInfo in context.TableMateInfos
                        select mateInfo;

I am using SQL Server 2008. I do not have any clue, why command execution should stop working after upgrade to .NET 4, especially because I am still able to connect to database. When I open DB in Management studio, SQL command (select * from TableMateInfo) works just fine and returns data I want. Does anybody have any ideas, where the burried dog might be please?

EDIT:

I have run my application by its' exe file, following exception has been thrown:

System.IO.FileLoadException: Mixed mode assembly is built against version 'v1.1.4322' of the runtime and cannot be loaded in the 4.0 runtime without additional configuration information.
   at System.Signature.GetSignature(SignatureStruct& signature, Void* pCorSig, Int32 cCorSig, RuntimeFieldHandleInternal fieldHandle, IRuntimeMethodInfo methodHandle, RuntimeType declaringType)
   at System.Signature..ctor(IRuntimeFieldInfo fieldHandle, RuntimeType declaringType)
   at System.Reflection.RtFieldInfo.get_FieldType()
   at System.Data.Linq.SqlClient.TypeSystem.GetMemberType(MemberInfo mi)
   at System.Data.Linq.Mapping.AttributedMetaDataMember..ctor(AttributedMetaType metaType, MemberInfo mi, Int32 ordinal)
   at System.Data.Linq.Mapping.AttributedMetaType.InitDataMembers()
   at System.Data.Linq.Mapping.AttributedMetaType..ctor(MetaModel model, MetaTable table, Type type, MetaType inheritanceRoot)
   at System.Data.Linq.Mapping.AttributedRootType..ctor(AttributedMetaModel model, AttributedMetaTable table, Type type)
   at System.Data.Linq.Mapping.AttributedMetaTable..ctor(AttributedMetaModel model, TableAttribute attr, Type rowType)
   at System.Data.Linq.Mapping.AttributedMetaModel.GetTableNoLocks(Type rowType)
   at System.Data.Linq.Mapping.AttributedMetaModel.GetTable(Type rowType)
   at System.Data.Linq.DataContext.GetTable[TEntity]()

I have added app.config file with following content to the same exact location where exe file and all libraries are located. Still I got the error above.

<?xml version="1.0"?>
<configuration>
    <configSections>
    </configSections>
<startup useLegacyV2RuntimeActivationPolicy="true">
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
</startup>
</configuration>

Answer 1

I think you have Linq namespace problem, Just do one thing

Go to [project name] -> References -> Add reference -> System.Data.Linq 

Add System.Data.Linq namespace by Add references .

Hope it solves your problem

Answer 2

Problem was in different versions of .NET used to build single projects after all. The app.config file above would work if there already weren't one without useLegacyV2RuntimeActivationPolicy="true" attribute. I had to add it manually, now it works perfectly.