mojira.dev
MCPE-184264

Fire spread mechanics by Lava are different to Java

The Bug:

Fire can burn wooden blocks that are at a seemingly safe distance from lava compared to Java. The fire spread mechanics involving lava are different between Java and Bedrock.

Steps to Reproduce:

  1. Build this structure exactly as shown. The glass panes should be placed right in front and right behind the exposed exterior faces of lava respectively. Do this before you place the lava block.

    [media]
  2. Break all the orange stained glass blocks except for the orange stained glass block that is one block directly above the lava.

  3. If possible, set your random tick speed to 40.

  4. Now break the orange stained glass block that is one block directly above the lava.

  5. Some wooden planks burn. ❌

  6. Now build that exact structure as shown in Java Edition.

  7. In Java Edition, break all the orange stained glass blocks. The wood will not burn. ✔

Expected result:

None of the wooden blocks should burn just like Java.

Observed result:

Some of the wooden blocks can burn compared to Java.

Linked issues

Attachments

Comments 6

This issue does not meet the criteria for the vanilla-parity label, but it does seem like a bug.

The differences of fire spread mechanics from lava can be explained. From Minecraft Wiki page:

https://minecraft.wiki/w/Lava#Usage

Java Edition:
Air block must be in a 3×1×3 area right above the lava or in a 5×1×5 2 blocks above the lava.

An air block in the 5×1×5 area does not catch on fire if the 3×1×3 area is completely filled, even if the latter is filled with flammable blocks.
Bedrock Edition:
The block to be set on fire must be in a 3×3×3 cube centered on a lava block, above which there must be either air or an ignitable block.

Hi!

Could you please record and upload a video of the issue?
Could you also please share how you suppress lava from spilling on the sides?

This ticket wil automatically reopen when you reply.

It is glass panes holding the lava in place. Here is a video. Looks like lava spreads fire downward in the same pattern it spreads upward. In Java it only spreads upward.

This issue causes the rear of weaponsmith buildings to spontaneously catch fire.

Screenshot 2025-12-19 113655.png

TheMightyDark

(Unassigned)

1457229

Confirmed

Multiple

java-parity

1.21.2 Hotfix, 1.21.94 Hotfix, 1.21.131 Hotfix

Retrieved