PaperMC / PaperMC/Paper

Exception when loading some old maps

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#12,566 2 comments 0 reactions 0 assignees View on GitHub

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status: needs triage version: 1.21.5
Dominant language
Java
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Forks
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Avg merge
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Merged PRs (30d)
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Description

Expected behavior

The map should load

Observed/Actual behavior

Exception: https://cpaste.de/raw/daraxareya

Steps/models to reproduce
  1. Add this map to your server (the exception is happening with many maps on our server but not all): https://webinterface.cubeside.de/temp/map_5423.dat
  2. Use the code mentioned here to load the map: https://cpaste.de/raw/daraxareya
  3. Join the server
  4. Exception: https://cpaste.de/raw/daraxareya
Plugin and Datapack List

just a test plugin

Paper version

This server is running Paper version 1.21.5-87-main@fa360aa (2025-05-18T22:35:50Z) (Implementing API version 1.21.5-R0.1-SNAPSHOT)
You are running the latest version

Other

No response

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

Start by reproducing the failure with map_5423.dat and the loading code from the linked cpaste, using Paper 1.21.5-87. Inspect the linked exception output and compare it with a map that loads successfully; done means the supplied old map and other affected maps load without the exception.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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