maintenance-page--offline template not working I am following this tutorial. https://www.drupal.org/node/195435.
I have created maintenance page and its working with admin configuration site under maintenance setting. I want to create dboffline mode maintenance page. so for that, i have created another tpl "maintenance-page--offline" in same directory where "maintenance-page.tpl.php" has created. Path is like sites/all/theme/mytheme/templates/.

previously it was working but currently its showing me Additional uncaught exception thrown while handling exception. error. Its not overriding maintenance-page--offline when i am disconnecting DB, by entering wrong password in settings.php file.
This is caused when class_exists() is being called from within alpha_get_theme() and autoloading fails. I have a patch that fixes this by wrapping those calls in a try/catch block. I'm not quite sure what should be done in the case of an error though, so I have just done nothing.

See theme Omega issue => https://www.drupal.org/node/1722586

It is working for me, I had the same problem.