I had this issue when moving my blog from one server to another:
1. Mysql database was out of date but the WP told me that and it was updated with one click.
2. Still blank, so i go to check the theme and I have a message that the ‘theme’ is broken.
3. Selected a default theme and activated it.
4. It worked! I can see the front page again, it was a broken theme, probably from the move.
Hope this helps somebody.
Matt