I've seen a lot of questions about pre 1.6 Magento installations to the most recent version (at the current moment 1.7.0.2) but there are a lot of answers that don't work for everybody.
So below the answer to the question: How to upgrade Magento from a pre 1.6 installation to the most recent one.
There are a lot of versions and not all of them are working. This one has worked for me for a lot of versions, as far as 1.3 to 1.7.
Please add comments with solutions to problems you're experiencing, I can update the answer so other people get help from this topic too!
What you need: - SUDO rights/root account on your server. - The linux package 'nohub' - make sure NOBODY can trigger the index.php. If your version supports maintenance.flag, put an empty maintenance.flag file in your Magento root.
1) Download the latest Magento. Overwrite: ./download/* ./lib/* ./mage
2) Run these steps from you Magento root als SUDOer (if you're not root, put 'sudo' for all the commands)
find . -type f -exec chmod 644 {} \;
find . -type d -exec chmod 755 {} \;
chmod -R 777 ./var
chmod 550 mage
3) Go to your Magento root folder and type:
./mage list-upgrades
./mage config-set preferred_state stable
./mage upgrade-all --force
./mage install http://connect20.magentocommerce.com/community Mage_All_Latest --force
4) Now there is the last step. Note: In some situations this process can take up to 8+ hours!
nohup php -f ./index.php
1) it's possible that your update gets in a loop. To find this loop, enable debugging.
Edit: /lib/Varien/Db/Adapter/Pdo/Mysql.php (+/- line 112 and 112)
protected $_debug = true;
protected $_debuglogeverything = true;
This will write a debug to: /var/debug/[debug_file]
2) Read the file by opening the dir:
cd /var/debug/[debug_file] <-- replace with the actual filename
tail -f [debug_file]
3) If you use debug, the file will get HUGE! Make sure you delete it once in a while.
Tip: as a root user, type:
crontab -e
*/5 * * * * rm /[my_magento_base_folder]/var/debug/[debug_file] <-- add this line
If you want to read the file, add a # to this line and use tail to read it.
These steps help you find common errors and loops (if the tail shows a repeating error message)