Why do I get SplFileInfo::getMTime()... errors in symfony2?

The error, in the browser, might look like this:

SplFileInfo::getMTime() [<a href='splfileinfo.getmtime'>splfileinfo.getmtime</a>]: stat failed for /var/www/html/Symfony/src/Srb/AnthonyBundle/Controller/.#DefaultController.php

If you are using emacs, make sure you save off all files.  If you don't, you might have a # file around, and symfony gets confused.