Upgrading wordpress can be a bit of a hassle especially if you are doing so using the wp-admin section. Here is the list of possible issues you may encounter during the core upgrade and quick ways to resolve these issues:
delete from wp_options where option_name="core_updater.lock";
The easiest and most preferable way to perform an update would be by having shell access to your host. I would recommend downloading the latest version of the wordpress. After this wordpress files should be extracted to substitute the existing files and update.php script should be executed from your domain name. Do not forget to backup your existing code and database before the upgrade!
Follow the instructions below to upgrade your wordpress:
mkdir /tmp/backup cd /tmp/backup
tar czf backup.tgz /var/www/[your site directory] mysqldump -uroot -p [database name] > database.sql
cd /tmp wget http://wordpress.org/latest.zip unzip latest.zip
cd /var/www/[your site directory] cp -avr /tmp/wordpress/* . rm -rf /tmp/wordpress /tmp/latest.zip
http://[your wordpress site]/wp-admin/upgrade.php
If something goes wrong, you can always locate your backup files in /tmp/backup , extract them , recover the database dump and go back to the previous state.
During the migration process and for other cases of wordpress troubleshooting it may be useful to turn on debugging. This can be achieved by switching these parameters in wp-config.php file:
// turns on debugging, output is displayed on the web page define('WP_DEBUG', true);
// the debug log will be saved to wp-content/debug.log define( ‘WP_DEBUG_LOG’, false);
Hope this helps :) enjoy migrating your wordpress site successfully !