I have recently updated to Visual Studio 2015. Opened up my solution and works. Till I decided to add in an entity to my edmx. So I double-clicked on the edmx file to open the diagram like it should or maybe the model browser at least but it only opens an XML page. I checked any missed installation from the setup but didn't find anything about entity framework there. I tried to create a test solution and create another edmx but ADO.NET entity is missing as well. What is going on? Am I going to revert back to Visual studio 2013?
For me, the sequence was:
If it opens as XML then it means that eventually XML Text Editor is set as default program to open edmx file. You can follow these steps to open in ADO.NET Entity Data Model Designer
and select open with and select the option as show in below image.