STEP 1. BACKUP YOUR EXISTING STORE FILES AND DATABASE!!! done
STEP 2. Upload ALL new files on top of your current install EXCEPT config.php and admin/config.php done
STEP 3. Browse to http://www.yourstore.com/shop/install done
STEP 4. The installer should direct you to the upgrade process. If you see the install steps, then you overwrote your config files. Restore them as the upgrade needs the existing config.php and admin/config.php files.
STEP 5. Click "Upgrade". After a few seconds you should see the upgrade success page. Follow the steps.it came with blank page but when refresh the store are working fine
STEP 6. Post any upgrade script errors problems in the forums
STEP 7. Clear any cookies in your browser to avoid getting token errors.
STEP 8. Load the admin page & press Ctrl+F5 twice to force the browser to update the css changes.done
STEP 9. Goto Admin->Users->User Groups and Edit the Top Adminstrator group. Check All boxes. done
STEP 10. Goto Admin and Edit the main System Settings. Update all fields and click save, even if nothing changed. done
STEP 11. Load the store front & press Ctrl+F5 twice to force the browser to update the css changes. done