There is a terrain generation problem when AntVenom tried (not me okay, i reported this but i don't do it) to set HeightScale to excessive levels (He tried to see the top of the X/Z-coordinate Far Lands). That's when he found out that (Y-coordinate but not X/Z-coordinate) Far Lands generated in the sky! He is surprised. He does that when his Minecraft is in modded version but later someone found out it also works on vanilla version of the Minecraft! That drives me some concern and that's why i created issue in here. I admit that i want this to be really fixed in 1.12 version of the Minecraft and such remove the Far Lands in the Y-coordinate completely. I liked the Far Lands but i don't want that to linger in vanilla version of the Minecraft and instead i want to keep that for the modded versions of Minecraft only. Here is the video: THE MINECRAFT SKY FAR LANDS?! by AntVenom on YouTube. Now i'll give the reason why Far Lands are generated, fixed and why Y-coordinate is not noticed.

Reasons
Based on Far Lands' article on Minecraft Wiki, it was said that the reason why it generates because when it reaches X/Z approximately 12,550,824 octaves of the Perlin noise overflows and WILL always use 2^31^-1, using that same noise and then generate that same terrain on it, resulting in a Far Lands. Then why on Beta 1.8 Far Lands (particularly X/Z-coordinate but not Y-coordinate) are removed? Because Notch for unknown reason when terrain generation is reformed and changed in that time he added an instruction that calls by taking the remainder of the input divided by 2^24^. With these, it can prevent the overflow caused by undeterred Perlin noise octave growth. However it was for X/Z-coordinate only but not Y-coordinate ones. This is because Y-coordinate Far Lands is unknown at that time! This is caused by the height limit, which prevents the blocks to generate higher than this limit. Discovery of Y-coordinate Far Lands is very surprising since i don't expect that Far Lands will ever generate in that area. What caused it? Actually, the fix of the Far Lands has not ever been applied for Y-coordinates which actually used the same Perlin noise system as X/Z did, except that it was limited because of the height limit i describe before. Reason? It was unknown to Notch at that time. Based on that article again, i say that one block amounts into 171.103 noise units (when in default CoordinateScale and HeightScale value which is 684.412). When that overflows, it generates Far Lands as expected. But, if you set the CoordinateScale and/or HeightScale higher one block can amount more than 171.103 noise units, which makes the Far Lands generate much more closer (e.g. if you make CoordinateScale double than default number it uses, it'll generate at X/Z 6,275,412! Evidence: download a mod from This, then use the Customized Worlds preset then set the CoordinateScale twice from default value and then teleport to these coordinates). Here is the video about it: MOVE the MINECRAFT FAR LANDS to SPAWN! by AntVenom on YouTube. The surprise discovery of the Y-coordinate Far Lands is all because of more Perlin noise units per block as expected by setting the HeightScale to high levels, the Perlin noise units aren't repeated per 2^24^ as it was on X/Z coordinates before (thus it worked on vanilla Minecraft), and the unknown status of this because of the height limit which prevents Y-coordinate Far Lands to ever generate.

How to reproduce the bug

1. Set the world preset into Customized World preset and customize it.
2. Go to the Presets and then go to the text box present at the top of the menu of presets there.
3. Search for the HeightScale setting in that box. If you found it, set it into 134217728 or higher if you want to make it closer, for example double that into 268435456.
4. Apply the presets and create the world!
5. LOOK AT THE TOP! (If you generate at the bottom of the Far Lands) or LOOK AT THE WEIRD TERRAIN! (If you generate at the top of the Far Lands). IT'S THE FAR LANDS! IN THE SKY?!

That's all! But before i end it, i want you to add this patch based on the instructions of how to fix it in the below.

How to fix it?
Please find the class that it was used for the X/Z terrain generator then download that mod based on that class which does have the instructions removed, then see differences between two. I'm pretty sure you can find the differences of it. After founding the differences between the two, you got the patch of what Notch used for fixing the X/Z far lands. And then, add that patch into the class that it was used for the Y terrain generator (you can guess it developers!) and DONE! Y-coordinate Far Lands "Far Sky" is gone for forever! At least...

Okay. I'm ending it here now. Sorry if there is no screenshots because i can't make the screenshot of that because my graphics card is broken and i reported this bug based on evidences from Minecraft YouTubers and not from myself (prove me, i can't do it on my laptop because the graphics card is broken). Anyway, i made the description TL;DR because i want to persuade you to fix it really before releasing 1.12. Sorry for some Far Lands seekers who will be shocked (after it was fixed) and irked because of me. To accommodate it i would like to see someone to release a mod based on previous unpatched class sometime after the 1.12 release is coming out. I'll end here right here, right now. Thank you!