I resolved this issue by setting database owner. My database did not have had any owner before this issue. Execute this command in your database to set owner to sysadmin account
use [YourDatabaseName] EXEC sp_changedbowner 'sa'
Tech Blog
Since 2004
Cannot execute as the database principle
My database did not have had any owner before this issue. Execute this command in your database to set owner to sysadmin account - August 9, 2018