Mixed mode assembly is built against version ‘v2.0.50727′ of the runtime

user_808487 0
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I'm getting the following exception:

Mixed mode assembly is built against version ‘v2.0.50727′ of the runtime and cannot be loaded in the 4.0 runtime without additional configuration information.

as I was trying to export crystal report from my WPF program...

I have added the following in the app.config already...

<startup useLegacyV2RuntimeActivationPolicy="true">
  <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
</startup>
<runtime>
  <NetFx40_LegacySecurityPolicy enabled="true"/>
</runtime>

Any experts can help????

Reference I found: http://www.davidmoore.info/2010/12/17/running-net-2-runtime-applications-under-the-net-4-runtime

.net-4.0 crystal-reports ado.net visual-studio-2010 .net
8 Answers

Please add attribute useLegacyV2RuntimeActivationPolicy="true" in your applications app.config file.

Old Value

  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.1"/>
  </startup>

New Value

  <startup useLegacyV2RuntimeActivationPolicy="true">
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.1"/>
  </startup>

It will solve your problem.

user_92034340

If the error happens with error column "File" as SGEN, then the fix needs to be in a file sgen.exe.config, next to sgen.exe. For example, for VS 2015, create C:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.6 Tools\sgen.exe.config. Minimum file contents: <configuration><startup useLegacyV2RuntimeActivationPolicy="true"/></configuration>

Source: SGEN Mixed mode assembly

user_1993640

Enabling the legacy from app.config didn't work for me. For unknown reasons, my application wasn't activating V2 runtime policy. I found a work around here.

Enabling the legacy from app.config is a recommended approach but in some cases it doesn't work as expected. Use the following code with in your main application to force Legacy V2 policy:

public static class RuntimePolicyHelper
{
public static bool LegacyV2RuntimeEnabledSuccessfully { get; private set; }

static RuntimePolicyHelper()
{
    ICLRRuntimeInfo clrRuntimeInfo =
        (ICLRRuntimeInfo)RuntimeEnvironment.GetRuntimeInterfaceAsObject(
            Guid.Empty, 
            typeof(ICLRRuntimeInfo).GUID);
    try
    {
        clrRuntimeInfo.BindAsLegacyV2Runtime();
        LegacyV2RuntimeEnabledSuccessfully = true;
    }
    catch (COMException)
    {
        // This occurs with an HRESULT meaning 
        // "A different runtime was already bound to the legacy CLR version 2 activation policy."
        LegacyV2RuntimeEnabledSuccessfully = false;
    }
}

[ComImport]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[Guid("BD39D1D2-BA2F-486A-89B0-B4B0CB466891")]
private interface ICLRRuntimeInfo
{
    void xGetVersionString();
    void xGetRuntimeDirectory();
    void xIsLoaded();
    void xIsLoadable();
    void xLoadErrorString();
    void xLoadLibrary();
    void xGetProcAddress();
    void xGetInterface();
    void xSetDefaultStartupFlags();
    void xGetDefaultStartupFlags();

    [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
    void BindAsLegacyV2Runtime();
}
}
user_58639380
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