Crystal reports error in SetDataSource

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

Add this code in app.config.

Try using this solution by adding the useLegacyV2RuntimeActivationPolicy attribute to your .config file

<startup useLegacyV2RuntimeActivationPolicy="true">