As ive looked through latest beta build, ive noticed than it had "4.5.1" folder which contains .NET 4.5.1,

But theres no .NET 2.0 or 4.0 setups anymore, is that the end for XP/2003?

(.NET 4.0 is the latest version supported by XP, while 4.5x is not supported anymore.)

i am not sure about windows server 2003, but i know that windows vista supports anything older than net 4.6 and is based on this OS. My best suggestion is to download an older version of the launcher that uses something older (if it ever did) which will run the client mostly the same as how the modern launcher will. you can also run studio from the executable in some cases if you need to.

All old Roblox clients (except 2019) are supported on Windows XP. And 2006-2007 clients are supported on Windows 2000.

Thank you all!

Now i got the clue what to do!

Currently i am planning a Longhorn build 5048 installation to see could it work on that version properly.