1) Check version release notes:
Check the version release notes from magento site. May be there is some special instructions for coming versions…
2) Backup your files
Backup all files manually or from linux shell. Before backup try to remove all cache files
3) Backup your database
mysqldump -u username -h localhost -ppassword database > my_database_name.sql
4) Disable cache from admin.
5) Delete cache and session directories located here:
6) Execute “clean” bash script located in /downloader/pearlib directory
a) Run chmod +x clean to be able to execute this script
b) ./clean to execute script
7) Finally go to Magento connect manager from your Magento admin
Paste this extension to upgrade Magento:
If its not working try below one in key field
After this is done, you should have new Magento, however if there was some custom coding, you should really know what is going on with your code.
Usually installation ends up with some minor problems that should be handled manually, sometimes even on default installations if you have really old version of Magento that you would like to upgrade.
8) Make proper testing before doing this production server
Step 6 is not necessary one…
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