Upgrade to Magento 1.6 via FTP

NOTE: “Always Backup your store files and database before upgrading.”

1. Download complete 1.6 package from magentocommerce.com and upload all the files to your magento (website) directory through FTP client.
2. After uploading all the files, if you receive server timeout errors, you can fix them by editing by nginx conf file.
3. After increasing timeout in server conf file, restart the upgrade by accessing website url from browser.
4. In case, you receive Mysql errors, then restore it back from your dump which was taken before starting upgrade.
5. Now restore your shop data and start your upgrade. Upgrading may take hours.
6. You’ve successfully upgraded to 1.6

Read more on Manual Upgrade

Related Topics:

1. How to Upgrade from Magento 1.5 to 1.6 on Wamp Installation
2. Upgrade to Magento 1.6 using Magento Connect Manager
3. How to upgrade from Magento 1.5.1 to Magento 1.6.0
4. Magento 1.6 Upgrade Errors with Solutions
5. Upgrade Magento from 1.4.x to 1.5.x or 1.6.x