1. Type in Service.msc in Run Command.
2. Once the Servcies App is opened. Look for MySQL57 Service. And restart it.
3. Then open MySQL WorkBench and in your database run the following SQL.
Where AjaxSamples is name of my Database.
set global optimizer_switch='derived_merge=OFF';
4. Restart the MySQL57 Service again.
5. Now in Visual Studio, Right Click and update the edmx and finally save it.