Guidance on Upgrading from DHTMLX Suite 8.1 to Suite 9

I am currently using the DHTMLX Suite 8.1 library.

We are planning to upgrade to Suite 9.
Before the official upgrade, I downloaded the trial version to check compatibility.

However, when running a project originally created with version 8.1, I encountered compatibility errors.

Could you please provide guidance on:
1. Whether the existing source code is fully compatible with Suite 9
2. The recommended procedure for applying and upgrading to the new library

Your advice would be greatly appreciated.