If you are facing problem while use both AX 2012 Feature pack and AX 2012 R2 clients at a time in your machine. Feature pack clients not supporting R2 client and vice verse then you try following. Yes Its right , there is no Microsoft Dynamics AX 2012 RTM component (AOS, client, Help Server, and so on) can co- exist with Microsoft Dynamics AX 2012 R2. Therefore, you must upgrade all components because there is no backward compatibility across components. http://www.microsoft.com/en-us/download/details.aspx?id=28701
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