WordPress Migrator "Transfer Failed Due To Database" Error
This error message is usually caused by a temporary MySQL connectivity problem on your host server. Restarting the transfer process after any MySQL connectivity problems are resolved should fix this.
Note that if your database has large tables the plugin may not be able to export them due to server-side restrictions on your host. Reducing the size of these tables should resolve this. You can find more information how to reduce the size of your WordPress database in this article.