edmx update not responding

Setting the compatibility level of the database to 110 has worked for me.

To check the compatibility level, run this script:

select compatibility_level from sys.databases where name = '<YOUR_DB_NAME>'
To set the compatibility level, use this script:

alter database <YOUR_DB_NAME> set compatibility_level = 110

https://stackoverflow.com/questions/32700540/update-wizard-not-responding