GD Rating System is not compatible with old and outdated GD Star Rating plugin. Functions, templates, shortcodes and widgets used with old plugin will not work with the GD Rating System.
Before we go on, most important thing to know is: GD Rating System is NOT update or the new version of GD Star Rating. GD Star Rating is old, outdated and no longer in development plugin (the last version is released way back in 2012 when WordPress 3.5 was released), that also has several security issues. That plugin will never get any updates and it should not be used due to outdated code, security issues and lack of support. GD Rating System is a completely different plugin (that happens to be made for the same purpose), and it has nothing in common with GD Star Rating.
Basic migration information
If you had any integration and customization made for GD Star Rating, that will no longer work with GD Rating System. And there is no way to convert the code or shortcodes from old plugin to new. But, with the help of the knowledge base, you can find appropriate replacements. The new plugin has may shortcodes, widgets and function that work in the similar way as they did with old plugin, but parameters and arguments need to be updated.
This process can’t be automated, you need to manually make changes required, code, shortcodes and everything else needs to be replaced.
Before you go on, make sure to check plugin settings. If you used 10 stars for GD Star Rating, and if you plan to use 10 stars in GD Rating System, adjust the settings for the number of stars. If you choose to use 5 stars or some other number of stars, that is no problem, the plugin will recalculate ratings on transfer.
Transferring rating data
GD Rating System can transfer rating data from GD Star Rating. GD Rating System Free edition can transfer data related to Stars Rating method. Pro edition allows you to transfer data for Stars Rating, Thumbs Rating, Stars Review and Multi Stars Rating method.
To transfer the data, you need to use Transfer Data panel in the plugin menu. From this panel, click on the GD Star Rating transfer tool, and once that panel opens, you will see instructions and options to configure the transfer of data for each available rating method. Data in GD Star Rating database tables will not be affected in any way.
Make sure to read the information on the transfer panel before starting the process. It is best to use this option as soon as you migrate to GD Rating System while there is no data stored, it is best to start with clean GD Rating System database tables to avoid voting conflicts, and to also make it easier to remove all data while testing.
Few more notes
There are some aspects that can’t be converted at all. New plugin uses different styles and images to display ratings, and it can’t use old styling. The old plugin used internal templates system to display ratings. That too can’t be used, the new plugin uses different templating system closer to system WordPress uses for themes. That too is covered in the knowledge base articles.