I was apply patch on Dynamics AX 2012 R3. During update checklist process. I found, Code merge check box was disabled. Message described that we need Team Explorer for Microsoft Visual Studio 2012 to enable it. Microsoft Official download link was not working.  I downloaded it from here, And it works for me. https://download.freedownloadmanager.org/Windows-PC/Team-Explorer-for-Microsoft-Visual-Studio-2012/FREE-   Remember, the above link is unauthenticated and third party, download it on your own risk. But some how the other we need to download it.