Import Products For Different Language From Very Old Version

Hello, a store owner with a very old version of CS Cart (v. 1.3.5) decided to upgrade and came to me for the process. So I setup a new store and then proceeded to export their products from the old store to import in the new.

The problem is that they have three languages English, German and Greek and from the old store I get 3 separate files. The import works by adding a language column in the csv files but when I select a product in the store and then try to change the language I get a 404 error.

Is there a special way to import the products or is it a settings thing?

Thank you!

You are in for a rough ride. I recommend performing the upgrade on a copy of your customers store. Upgrade their store to 2.2.4 then use this addon upgrade to 4.7.2. After that you can do the regular incremental upgrades to the latest version.