Your Site should not really be on Joomla 1.5 Version anymore, but the fact is there are still a lot of sites around build with Joomla 1.5.
Some, because they like the look and template they use (which might not work on a later version of Joomla like Joomla 2.5 or Joomla 3.xx
Some, because the site is working and they are happy with it and do not see a reason to upgrade.
The Main Reason to upgrade your Joomla 1.5 should be SECURITY.
With each new Version some Security Holes a Hacker could exploit are plugged.
The following are step by step instructions to migrate your 1.5 site to Joomla 3.x. While there are many ways to migrate your site, this will give you the basic procedure to follow.

The migration from Joomla! 1.5 to 3.x is a major migration. There are many changes in features and database tables between these two version. It is NOT a one-click update. You will be building/installing a fresh Joomla! 3 installation and then migrating (moving) your data into it. If you haven’t already, you may want to start with the Self Assessment and Planning documents.

Let’s first distinguish between Joomla Core data and third-party extension data. Joomla Core data (components) are:

• Categories
• Articles
• Menus
• Modules (core modules – not third-party)
• Banners
• Contacts
• Messaging
• Newsfeeds
• Redirect
• Search
• Smart Search
• Weblinks

Step by Step

Moving Joomla core data is fairly straight-forward with the use of a migration tool. Everything else is a third-party extension or a custom built extension. This includes the template. Each third-party extension needs to be researched to determine if it’s ready for Joomla 3.x and has a migration path or not. You may have done this in the planning process. If not, you will need to do it now. Some third-party extensions can be migrated with a third-party tool. Some cannot. Read. Research. Plan.

Since there are many ways to migrate data and each site is different, the exact steps are going to be slightly different for every site.

Prepare a Location for Joomla 3

1. Make sure your server environment meets the technical specifications for Joomla! 3 before proceeding.
   Note: If your host does not meet the technical requirements, you will need to change hosts. If you need to change hosts, then set up a new hosting account on a host that meets the technical specs and install your fresh Joomla 3.x site in the root of the server on a temporary domain. This will make it easier when it’s time to go live. Alternatively, you can set up a development location on a local device (see below).
2. Create a new database and new user for your Joomla! 3.x site. Document the database name, database username and database password as you’ll need it when you install Joomla 3.

Set up a Development Location

1. Create a testing site or build area to work in with one of the following:
   • A subdomain
   • A subdirectory
   • A local device via WAMP, MAMP, LAMP, XAMPP.
   • A new hosting account on a temporary domain in the root (if you would like to change hosts in the process of migration)
     • Restoring a site on a local device.
     • Restoring a site with Akeeba Backup (read the developer documentation or videos for how to restore a backup of an Akeeba Backup file).
   • Install a fresh installation of the latest version of Joomla 3.x into your testing site location using your new database name and database username. (Get the latest version of Joomla! 3)
     WARNING: DO NOT INSTALL SAMPLE DATA!
     NOTE: If you will be migrating any of the core extensions that will be decoupled from Joomla! 3.4+, then you will need to install Joomla 3.x AND the core supported extension. Core supported extensions will be accessible via the JED (extensions.joomla.org) and via the Install from web tab of the Extension Manager. Make sure you install any core supported extensions before migrating data. See the Roadmap for more details on what will be decoupled/removed.
   • Run a backup of your Joomla 3 site. (Backup Basics for a Joomla! Web Site or see Suggested Tools)

Prepare Your Current 1.5 Site

1. On your 1.5 site, update it to the latest version 1.5.26 after backing it up.
2. Empty the trash in the content manager (sections, categories, articles), menu manager, module manager.
3. Clean up your sections, categories, articles, modules, menu items. Make sure they all have unique aliases. Empty the trash again if necessary.
   NOTE: Sections no longer exist in Joomla 3. Sections become a parent Category. Categories become nested categories of the parent category.
4. Notify users that any changes on the current site from this point forward will have to be reentered on the new site. For very complex migrations with changing data constantly, see this magazine article and this video.

Choose a migration tool

1. There are many migration tools. Some are free, some cost a bit of money. Some only migrate certain data. Some migrate more types of data than others.
2. Each migration tool will have their own step by step documentation on how to move data (if they don’t then don’t use it). Some migration tools will require the 1.5 site and 3 site on the same server. If you’re switching hosts, you will want to restore a *subdomain* of your 1.5 site on your new hosting account to pull the data from. Then kill it when you’re done.
3. Migration tools can be found at the Extension Directory.
4. When you choose a tool, choose one that allows you to keep the ItemIDs the same in the migration process. This is necessary to keep your search engine ranking intact or you may have more redirects to do. More information on redirects follow.
5. If you have a small site, you may want to do the migration manually. Create categories and articles and copy the html over into your new site. Then copy the image directory over. Keep the /stories directory or your image links will be broken until you fix each one.
6. One of the migration tools (a free one) allows you to bring articles and only images associated with those articles over. This is helpful if your Media Manager is out of control.

Migration

1. Migrate all core data you want to move to Joomla 3.x. If your migration tool asks to move Sections and Categories, definitely do both. The conversion will happen to categories and nested categories automatically.
2. Run the Database Fix by going to Extension Manager → Database and click the Fix button in the top toolbar.
3. Install your new template or converted template so that you can see your content. See more about Template Considerations.
4. Add new menus if the tool you chose to use didn’t bring over menus. If you want to use split menus, set that up now.
5. Add modules if the tool you chose to use didn’t bring over modules. If the tool you chose to use did bring over modules, change the module positions to the positions in your new template if required so that your modules show up and you can see what you’re working with.
6. Check for duplicate alias issues and fix them.
7. Check your internal links. If any are broken, fix them.
8. Take a backup.
9. Install other third-party extensions and configure them (like editors, Akeeba backup, slideshows, or plugins).
10. Take a backup.
11. If you have large extensions with data to migrate, do each one according to the developer documentation and then take a backup after each one.
12. If your migration tool didn’t move the images, you will want to move your images from the 1.5 site to the 3.x site. Note: keep the /stories directory unless you want to relink all your images. You can start a new organisational structure in the /images directory from here forward if stories is a mess.
13. Recommended but not required unless you have issues: Fix asset issues. See below for a helpful tool.
14. If you are going to add anything to your site or use new core features like Tags, get them set up and configured at this time.
15. Check your URLs on the Joomla 3 site and compare to the Joomla 1.5 site. If they are different, document each (an excel spreadsheet is helpful) 1.5 URL and what Joomla 3.x URL they will be going to so that you can do redirects and keep your ranking. See:
    • Migration SEO Tips Series – Part 1 – Planning Your Link Migration Strategy; and
    • Migration SEO Tips Series – Part 2 – Monitoring Your Migrated Site’s Health.
16. Take a backup.
17. Check everything.
18. Clean up more.
19. Test everything.
20. Take a backup.
21. Move or change or add updated data from the 1.5 site to the Joomla 3 site.
22. Add google analytics to the template or use a third-party plugin.
23. Check Global Configuration and make sure all is as it should be.
24. Take a final backup of the Joomla 3.x site.
25. Take a final backup of the 1.5 site.
26. Move your 1.5 site from the root to another subdomain or subdirectory or simply delete it (this is so that you have it again for a brief time if you need to refer to it).
27. Backup and restore using a suggested tool (below) or simply move files to restore your 3.x site to the root of your hosting.
    NOTE: If you are changing hosts, then you can leave your Joomla 3.x site where it is and simply change nameservers on the domain to make it live. Make sure you’ve addressed any email issues first.
28. Enable .htaccess if necessary for SEF URLs.
29. Create a sitemap and submit to Google Webmaster Tools or any other search engine you would like.
30. Do all your redirects from the spreadsheet you created earlier for URLs that changed in the migration process.
31. Make any other changes that needed to wait until the 3.x site was live.
32. Test again.
33. Take another backup.
34. Kill any instance(s) of the 1.5 site as soon as possible.
35. Remove all other dev sites you may have been working with or keep them up-to-date if they are running a current version in order to ward off hack attempts on your server.
36. Welcome to Joomla! 3.x!

Suggested Tools

• Akeeba Backup for backup and restore.
• ACL Manager to fix asset issues in a few clicks.