OK, I’ll get us started, your thread title will draw in help but you must try to help us help you first.
Please, what is version you upgrade from and which 2.4 version (stable/snapshot) upgraded to?
What is your platform / operating system ?
Java version?
Explain problem more fully
You said ‘control of existing devices works’, zigbee existing zigee devices or just in general other devices? You said scanning provides nothing, do you mean discovery of new zigee devices?
see here for how to set logs to debug
see here for how to ask a good question
And for the love of everything that is holy please try to use code fences when you post your logs, item files and other assorted stuff people will ask you for now and forever more
(so Vincent doesn’t flip out)