When you’re migrating WordPress (or any other platform using serialized PHP strings in the database) between domains, you must use a safe search and replace method that preserves the integrity of the serialized string lengths. A simple of a dump file for http://localhost to, for example, http://thenewdomain.com is problematic because the length of the string changes but the indexes for the serialized strings does not. Consequently settings are lost and widgets disappear. Not good.