Mixed mode assembly is built against version ‘v2.0.50727′ of the runtime
.net, .net-4.0, ado.net, crystal-reports, visual-studio-2010
Solution
Try to use this exact startup tag in your app.config under configuration node
<startup useLegacyV2RuntimeActivationPolicy="true">
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
<requiredRuntime version="v4.0.20506" />
</startup>
Problem
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