Migrating Joomla 1.5 to 2.5 might be a complex process, depending on what extensions you have on your current website. It's almost never a one-click process. The same goes for Virtuemart. VirtueMart 2.x.x is a completely new shopping cart system which is not compatible with VirtueMart 1, and a one-click upgrade does not exist.
First of all, make sure you have a complete backup of your site (I recommend Akeeba Backup)
There are many ways to do the migration, I'm going to list a couple of alternatives, but first keep in mind the following:
- Your current template will most probably not work with Joomla 2.5. You'll have to:
- modify it to make it compatible
- download a new version from the template provider (if available)
- use a different template
- You'll have to look for an upgraded version of most of your extensions.
- Virtuemart 2 does not use templates like VM1 did, any layout overrides comes from your Joomla template.
1. Build a new site
Taking into account the points above, you might be better of creating a completely new site. Then use J2XML to import articles (with images), categories, menus and users. This will give you a kickstart, and the advantage is that you have a very clean J2.5 installation.
Then install Virtuemart 2, and set up your products again. If you have few products, I think this is the easiest way.
2. Use Virtuemart 2 Migrator
DISCLAIMER: I haven't tried this component myself
Virtuemart 2 Migrator is a commercial extension that claims it can migrate both Joomla and Virtuemart.
This migrator, is a giant leap towards Joomla 2.5 and VirtueMart 2 !
Every VirtueMart content from your shop will be copied over. Here is
how it works.
- Install blank Joomla 2.5 and VirtueMart 2 on the same server as your existing website
- Install VirtueMart 2 Migrator component and configure database access and file paths
- Select the contents you want to migrate and hit the "Migrate now button"
Try other migration tools
A list of different tools for Joomla migration is available at JED. As long as you work on a copy of your site, there's nothing wrong with testing different solutions (except it might be time consuming).