1. Download the package from Github because the website packages contains additional modules which isn't working in a sub directory as they are for commercial purpose. https://www.prestashop.com/forums/topic/1085022-unable-to-install-prestashop-81x-in-a-subdirectory/
(The release package for 9.0.0 wasn't available on Github https://github.com/PrestaShop/PrestaShop/releases/tag/9.0.0 and in relase notes link on Github i.e https://build.prestashop-project.org/news/2025/prestashop-9-0-available/ they have mentioned to download from https://prestashop.com/versions/
2. Keep root writable while installing manually.
3. Unzip prestashop files on server only. Let UI unzip the files. Before starting the installation make the zip on server and download.
4. [IMP] TAKE SQL DUMP WHEN INSTALLATION COMPLETES AND FILE DUMP ON ADMIN PANEL
5. check and 
	copy /admin/bundles/*
	copy /translations/* [Not required anymore]
	copy config/themes/* (Except config/themes/classic/shop1.json, need to configure this file) (Not required from 1.7.1.0)
	copy img/*
	copy mails/en/* except files which uses softurl
	copy modules/* except files which uses softurl
	Delete /var/cache/prod
6. Copy bootstrap.php from config folder and create _bootstrap.php and make following changes to get new_cookie_key :
"echo '<new_cookie_key>'.$key.'</new_cookie_key>';"
This is our change to generate the new_cookie_key, Also create clone_bootstrap.php and make changes to unset new_cookie_key>
7. If it is asked for country choose "United States" and Shop timezone as "US/Eastern"
8. Keep demo data "enabled" and SSL entry "blank" in manual installation.
9. While manual install - installation of modules : Install all modules (recommended)
10. PHP REQUIREMENT LINK: https://devdocs.prestashop-project.org/9/basics/installation/system-requirements/#php-requirements
11. No Documentation provided to upgrade prestashop 1.7.x.x hence we have not provided the same. http://doc.prestashop.com/dashboard.action
12. We have removed mcrypt extension because a user reported this via ticket.
13. [NA] config.php generates on visiting frontlink in manual installation.
14. Under [[dbprefix]]configuration table keep 'value' column blank for the following 'name' columns i.e : PS_ACCOUNTS_RSA_PRIVATE_KEY, PS_ACCOUNTS_RSA_PUBLIC_KEY and PS_ACCOUNTS_RSA_SIGN_DATA blank , as they are made again after logging into the admin panel.(By clicking on Modules-> Marketplace)
15. [NA] For our reference : Since Presta 8.0.1, while manual installation Prestashop is installed in maintenance mode and demo data isnt displayed . We have kept the same. To enable store users will have to go to admin panel -> click maintenance mode icon and check 'Enable Store' to enable store and display demo data content on frontend. (Requires in Prestashop commercial package)
16. Select 'classic theme' while manual installation.