Quantum Leap... Large Custom Site, Upgrading to 3.5

[dataclarity]

Would like to get an idea of what needs to happen in what order for my task.

We have a very large site (approx. 900 articles/pages). Since the beginning, and even more over the years, the site has been extremely customized by design, extensions, and complete custom coding. As a result, we never kept our Joomla up to date for fear of breaking extensions and other custom coding. We are currently running, 2.5.11 and we are ready for a brand new, up to date site that is based on 3.5 and all its' supported extensions.

My question is this... what should be the process for creating the new website while keeping our content? Do we obtain a new Joomla installation in a new location (what would equate to being a 'sandbox' install), then export and import the existing site/database into the new install, then overlay a new responsive template (from a proven company, like YOOtheme) and work the content to fit the new template 'behind the scenes', and finally link our domain to the completed new site?

I'm just not sure and value any expert opinions. Please advise.

[sovainfo]

Suggest you have a look at docs.joomla.org for migrating information. The procedure you are proposing omits dealing with your customizations, the reason you did not update!

[Webdongle]

For a large site and professional migration http://extensions.joomla.org/extensions ... p-transfer

However if you have edited core files and/or the database structure then you may experience problems ?

It may be just as easy to export the Categories/Articles Users with an extension then import into a fresh Joomla that has no sample data.

In either case ... if you have a custom Template with overrides then that will probably need editing before installing it into a new Joomla.