SmashPortal

To add to the complaint list, this makes mobs spawn on blocks that otherwise seem to be within the boundaries of a mushroom island.

Confirmed for 1.18.2 

In my first example, I was experiencing the issue with an unmodded client on an unmodded server.

Because I'm unable to recreate this in vanilla singleplayer in my attempts, let me list what I know:

The first server I played on was created in 1.16.3 with no mods (I helped the host set it up a couple months ago, and they didn't even know what Bukkit was when I was talking about this ticket to them earlier). I played on the server initially with Optifine, then we both began using Forge with a minimap mod. The server was still unmodded. Port forwarding wasn't an option for the host, so they ran ngrok so that I could connect to the server. When I ran into this issue, I swapped to a strictly vanilla client, and still noticed the issue.

Today, I was playing on a 1.16.x server. I was able to connect with vanilla 1.16.5. The new server is running some form of modded server file (it has several special commands), but I don't think that takes away from the same issue occurring as on the first server.

In this screenshot (on the newer server), the biome at Y=55 is mushroom_field_shore:

In this screenshot (taken at the same X and Z coordinates), the biome at Y=63 is lukewarm_ocean:

Perhaps this is a caching issue, where the biomes are cached from when I discovered them while using Optifine? In my first instance, I was able to see the issue with a vanilla 1.16.3 client on a vanilla 1.16.3 server, then in the second instance I was able to see the issue with a vanilla 1.16.5 client on a lightly modded 1.16.x server. In both instances, I discovered the terrain with an Optifine client, but swapped to a vanilla client and still had the issue.

In both cases I've experienced, it was a server. I can vouch that the the first server was 100% vanilla, though. I haven't attempted to reproduce in singleplayer, so I don't have a seed.

Edit: I'll see what I can do to reproduce in singleplayer.

This is a Forge 34.1.0 bug.

Just to clarify, it's not related to Optifine.

Yes. I guess this is an older bug.

I want to add to this something from my duplicate report: if you place a frame next to where the bad portal would spawn, then put an eye in that frame, it relights the portal (even if the portal's already there).

See the last two images from this ticket: https://bugs.mojang.com/browse/MC-167157

If intended, it should be documented on the Official Minecraft Wiki, as right now it doesn't match the current game state.

To the mod, I believe this person is talking about the World selection list (like this http://i.imgur.com/ipAnk.png). I think they're saying that their worlds aren't showing up there, even though the worlds are still there in the saves folder.

Is Twitch connected to your Mojang account?

Confirmed, was testing beacons below spawners to see if they'd still radiate effects. Couldn't get it to accept my emerald or diamond.

Cool. I couldn't figure out how to search for it, and wasn't getting any results in quicksearch.

Confirmed for 14w27a

Also trapdoors place weird on top slabs

https://dl-web.dropbox.com/get/Screenshot_2014-06-10-20-38-04.png?_subject_uid=197618648&w=AACRVybfNzCoMsDZfIQr5Jq-4SZY-DxP_zelReKHtM4Cnw

Still an issue in 14w20b, only seems to affect Redstone Ore, though.

If you just switched to the snapshot from an older version, the world terrain generation may have changed, therefore chunks that weren't loaded before would load with different coding than the chunks around them that were loaded in the past version.

You need to have a repeating Redstone pulse going into the Command Block for it to keep testing. Otherwise, it will remain "on" until it receives a Redstone signal. (Try putting "/setblock ~ ~+1 ~ redstone_block 0 destroy" into a Command Block and input a Redstone signal of some sort on top. This will create a very quick Redstone pulse - then hook up Redstone to it. You can also power other sides of the Command Block, only if the setblock co-ords are to that side.)

Thank you for listening and re-opening the original.

Here is a link to the original post that was labeled "Resolved, duplicate", even though it wasn't: MC-46229