No Biomes sub folder in Behaviors Pack

Thank you for your report. However, this report is Invalid.

I looked back through all the sample vanilla behavior packs since 1.11.3. There has never been a Biomes sub folder included in the sample packs, so your statement that it no longer exists is apparently based on a false recollection or assumption. What you've described is therefore not a bug.

You probably expected to find vanilla versions for the built-in biomes that you could copy and modify, a technique often employed by pack makers, but that doesn't work for biomes the way it does for most elements of the game. The vanilla biome parameters are in a file named "biomes_client.json", but your pack is not allowed to override that file because of how tightly integrated biome generation is with world generation. Instead, you can override some of the parameters by adding a Biomes folder to your pack and putting individual JSON files in it for each biome you want to modify.

However, I think you're looking in the wrong place, since you say you want to change the spawning rates. The biome parameters define which mobs can spawn in a biome, but not how and when spawns occur. Rules for spawning are defined per mob type, and are governed by JSON files in the spawn_rules folder. Whether you can accomplish what you want to do with those files depends on what exactly you want to do. I believe you can change the balance between the various kinds of mobs that spawn, but I don't think you can actually increase or decrease the overall rate. However, we've now gone beyond the scope of the bug tracker; you should look to community help resources for information on how to use the spawn rules.

I haven't actually tried to use any of this add-on technology myself, so some of my comments above might not be perfectly accurate. I'll continue to monitor this report in case
more clarification is needed.

Hi Auldrick, the reason I posted this bug is that my friend and I wanted to do a infinite desert survival world by following the instructions at the bottom of this wiki:

https://minecraft.gamepedia.com/Tutorials/Survival_in_an_infinite_desert

The problem is that the instruction state you change the desert.json file to make a infinite desert world but there is no file of that kind in the behavior Pack.

The wiki tutorial is poorly written and a bit misleading. It says that you can modify the desert biome generation by editing the desert.json file in the biome subfolder. That's true, except that the subfolder name is "biomes", not "biome".

But the bigger problem is that you're assuming "editing" the desert.json file means "copying and modifying" it, the way some people copy and modify other template files when making an add-on. You can't do that for biome generation, because there's no file to copy; you're supposed to create it yourself, along with the biomes subfolder. The instructions for creating biome files are provided in the behavior pack template, in the documentation\Biomes.html file.

I realize this makes customizing biomes inherently more difficult, but it's actually the way you're supposed to create all add-ons. Copying and modifying template files is easier, but it will eventually backfire if you don't understand exactly what's going on behind the scenes, and that understanding will only come by studying the documentation.

You'll probably have many questions while trying to understand the documentation. Please keep in mind that the bug tracker is only for reporting bugs and is not the place to come for answers. Instead, you should use community resources such as the MCPE sub-Reddit or the Minecraft Discord.