attempt to re-open an already-closed object: SQLiteDatabase: (database path)

Hello,
Thanks for the nice article.
Gives a great understanding of the room migration.

However, when I tried to add the DB migration, I am getting the same error like,

> java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase: (database path)


Can you please help or guide me that what can be the possible causes?

Thanks.