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  1. Minecraft: Java Edition
  2. MC-118857

Effect amplifier is read/written as byte from NBT despite being stored as an integer

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Details

    • Icon: Bug Bug
    • Resolution: Unresolved
    • None
    • Minecraft 1.12, Minecraft 1.12.1 Pre-Release 1, Minecraft 1.12.1, Minecraft 17w50a, Minecraft 1.13.2, Minecraft 19w04b, 1.16.4, 20w46a, 21w06a, 21w16a, 21w17a, 1.17, 1.17.1 Pre-release 2, 1.17.1, 21w44a, 1.18.1, 1.18.2, 1.19, 1.19.1 Pre-release 4, 1.19.2, 1.19.3, 23w03a, 1.19.4 Pre-release 2, 1.19.4, 1.20 Pre-release 6
    • Confirmed
    • Entities, Save Data

    Description

      The bug

      Effect amplifiers are read as byte (-128 to 127) instead of as an integer (-2,147,483,648 to 2,147,483,647) from NBT.

      How to reproduce

      1. Give yourself jump boost with an amplifier higher than 127 using /effect 
        /effect give @s jump_boost 100 128
      2. Try to jump
        → You cannot jump (see also MC-90198)
      3. Reopen the world
        → You now have jump boost with an amplifier of -128 when read (though will be considered 0 when an amplifier obtained via NBT is less than 0)

      Code analysis

      Based on 1.12 decompiled using MCP 9.40 PRE 1

      The methods net.minecraft.potion.PotionEffect.readCustomPotionEffectFromNBT(NBTTagCompound) and net.minecraft.potion.PotionEffect.writeCustomPotionEffectToNBT(NBTTagCompound) reads/writes the amplifier as a byte, while it is stored in-memory as an integer.

      Attachments

        1. 2023-02-16_21-59-23.mp4
          7.15 MB
        2. 2023-02-16_21-59-23-1.mp4
          7.15 MB

        Activity

          People

            Unassigned Unassigned
            marcono1234 [Mod] Marcono1234
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            15 Vote for this issue
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            Dates

              Created:
              Updated:
              CHK: