PaperMC / PaperMC/Paper

Projectiles stop tracking when players move into them

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#12,889 4 comments 0 reactions 0 assignees View on GitHub

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status: needs triage version: 1.21.8
Dominant language
Java
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Description

Expected behavior

The projectile should keep tracking, instead of phasing to where it lands.

Observed/Actual behavior

https://youtu.be/pxklrZbF_R4

Steps/models to reproduce

Shoot arrows while moving forward on a 1.21.8 paper server with no plugins, the arrows will desync. This bug does not happen on 1.21.8 vanilla

Plugin and Datapack List

None

Paper version

This server is running Paper version 1.21.8-11-main@a5f2f61 (2025-07-22T08:53:33Z) (Implementing API version 1.21.8-R0.1-SNAPSHOT)
You are running the latest version
Previous version: 1.21.4-DEV-25e1915 (MC: 1.21.4)

Other

Maybe related to https://github.com/PaperMC/Paper/issues/12200

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the arrow desync on Paper 1.21.8-11 with no plugins while moving forward, then compare the result with vanilla 1.21.8. Read the related issue #12200 and trace the projectile tracking path; done means arrows continue tracking players instead of phasing to their landing position.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
game-dev
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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