I highly doubt they've randomly decided to hardcode it when it hasn't been hardcoded in -any- previous versions. This sounds like you don't have the char racial variation data, in the DBC/2 files.

I can't 100% say it's hardcoded. But the problem also exists in MoP. The same error exists on races, if you try to add a new id. However if you use the existing race id's. they will work just fine.

What dbc/2 do you exactly mean? I looked fort about 5 hours to find them all. I changed. CharBaseInfo and CharClasses

If you haven't yet updated the gt tables (GtOCTBaseHPBylass for example), try to do that. Also add the class in "class_expansion_requirement" in the world database.

Quote from: "Ghaster"

Damnit they discovered that?
Use my modified exe http://modcraft.io/viewtopic.php?f=59&t=9218 The difference is that the data folder now works as the MPQ, so just extract the modified patch file to the data folder.

Wont this still DC if nost is checking the MPQ files in the data folder?

You are gonna need to restore to the original patch file. But instead of having files like this:
WoW FolderDataPatch-2.MPQCreatureCowCow.m2
It's now gonna be:
WoW FolderDataCreatureCowCow.m2

Update player_levelstats table and update your server dbc files.

Try updating CharSections with your new races.

This doesn't seem to work properly in 5.4.x. It works on 4.3.4, 5.0 and 5.1. I haven't tested 5.2 or 5.3.
The patch applies fine, however it doesn't load anything at all. Nothing.
The only thing i found possible to load in 5.4 from the data folder is GlueXML edits. Whenever i replace a dbc file, update a m2 model or add new adt's, it doesn't load them at all. I have tried doing the edits multiple times, same result.

Does anyone have an idea why this is happening?

EDIT: Okay i think something has changed. In earlier versions, the pattern is at 1410h or something while in 5.4 it finds the pattern at D:1E9Dh. The pattern has most likely changed in 5.4.x.

EDIT EDIT: Managed to fix it:
To make this patch work on 5.3 or higher, you have to do this:
Find 7BFAh, and write 90 90 90 90 90

If you want the new WoD Models on Vanilla, you are gonna have to fix the uvmapping (http://modcraft.io/viewtopic.php?f=20&t=8564) Once done, you will need to fix all the textures for the model, to fit the vanilla format, use the tutorial above, and resize the texture to half (eg. if the body texture is 512x512, you need to resize it to 256x256.)
When you have done that, you will need to fix CharSections.dbc. No easy way to do this, but just compare the two and you will find out easily.

When all that is done, the finished result should look something like this:

Try using this version of M2Mod instead:
http://modcraft.io/viewtopic.php?f=59&t=8864