Hello guys, this is my first guide post, I did search so It shouldnt be a repost, but let me know if it is.
I found this out when I had a 2.4.1 server and a 2.4.2 core, and it was spitting out the "Cannot Validate Version" error, even tho with such a small update it should be fine! (Major point releases might not be reccomended for this though)
You will need to compile realmd, if you are using a repack and don't know how to compile a MaNGOS server, this guide might not be for you.
This guide assumes you have Visual C++ Express 9.0 for compiling, and some sort of way of checking out the latest SVN revision of mangos.
1: Check out the revision of MaNGOS that matches your realmd and the rest of your server. I use tortoiseSVN for this. I will be assuming that you have the source in C:\MaNGOS-Source
2: Browse to \src\realmd, the file you want is called AuthCodes.h
3: Open WoW, there are build details in the bottom left hand corner, there are 4 digits in brackets, remember them.
4: Go back to your authcodes.h file, and scroll down to the bottom. Edit the numbers in red to the numbers you remembered earlier, Don't edit anything else.
5: Browse to \win and open mangosdVC90.sln
6: Change the build mode to "release" from debug. Do this by going to Build -> Configuration manager. Then change build mode from "Debug" to "Release"
7: Then right click "Realmd" on the right pane and click Build, it will then compile the new realmd.
You will see the message when it's successfully compiled
8: Once it has finished compiling, the realmd will be in \bin\Win32_Release\realmd.exe. Just copy that file to your server directory and run it.
Let me know if this helped you!