Sửa lỗi update-database code first "there is already an object named"

update-database -verbose doesn't work because your model has been changed after your data table already existed.

First, make sure there are no changes to the UserProfile class. Then, run:

Add-Migration InitialMigrations -IgnoreChanges

This should generate a blank "InitialMigration" file. Now, add any desired changes to the UserProfile class. Once changes are added, run the update command again:

update-database -verbose

Now the automatic migration will be applied and the table will be altered with your changes