Upgrading Magento from 1.1.8 to 1.5 stable

Am looking to upgrade Mangeto from version 1.1.8 to version 1.5.

This is a quite a leap 开发者_如何学CI am taking I know, but and I have tried the following already (as some one else had suggested on another site):

• dump v1.1.8 database, restore it in a new database.
• install magento 1.5 pointing on the restored v1.1.8 database
• let the upgrader run
• add the old theme files
• test that it all works.

When doing that, the upgrader kept saying some tables already existed.

Can anyone help me out?

Thanks

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It's fine now, basically make sure you're using the same server environment.