When I put Immersive Railroading and try to load or create a world minecraft tells me something is wrong with my data packs and just refuses to load anything, even pressing the safe mode button does nothing at all and when I take the mod out everything works fine. It doesn't work regardless of what other mods are present and it also doesn't create a crash-log. I have no idea what is going on here and for other people it seems to work fine. Please help

Larky's suggestion should work, and this bug should be fixed in the next version

Close MC down, delete config folder, restart MC