I'm running a apache2 server on Ubuntu. While I was in the middle of configuring new content on my local instance of drupal via Firefox, the site suddenly stopped working. My first thought was the the apache2 server was down, so I restarted it. Then I created an index.html, and index.php that both worked (outside the drupal directory).
Now let's say I go to localhost/drupal/ I get a blank page. However, if I go to localhost/drupal/update.php I get the update page. I found that out as I was trying to figure out if any page would load. /index.php does not work.
Any idea to what I should investigate next? What's weird is that I was in the middle of working on the site when it went down. I don't see a reason for that to happen.
Any help is appreciated.
Update: I found that apache log can be handy. By typing into the terminal:sudo cat /var/log/apache2/error.log
I found that the log had the following error:
PHP Fatal error: Cannot redeclare class QueryConditionInterface in /var/www/html/drupal/includes/database/query.inc on line 16
I tried replacing this file with the file from the original drupal package, didn't work. Nor should it have because I didn't change any code in this file.
Things I've tried:
Restart mysql and appache2 using
sudo service mysql restart
Delete /drupal/includes/ and re-populate it with files from the original