Trial Chambers vaults generated before 1.21.11 become permanently inactive after updating from Paper 1.21.10 to Purpur 1.21.11

[tabatintores]

Spark link

https://spark.lucko.me/UZrNtnMp5h

Expected behavior

Trial Chambers vaults generated in existing worlds should remain functional after updating the server.

After updating from Paper 1.21.10 to Purpur 1.21.11, previously generated Trial Chambers vault blocks should accept trial keys and activate normally, without requiring manual regeneration or block replacement.

Observed/Actual behavior

After updating the server from Paper 1.21.10 to Purpur 1.21.11, all previously generated Trial Chambers vault blocks became inactive.

Vaults do not react to trial keys at all and cannot be opened. The blocks appear permanently inactive/locked.

If the affected chunks are regenerated using //regen, or if the vault block is manually replaced with a newly placed vault block, the vault works correctly again. Newly generated Trial Chambers are also fully functional.

Steps/models to reproduce

1. Start a server on Paper 1.21.10.
2. Generate Trial Chambers in the world (do not regenerate or modify them afterward).
3. Stop the server.
4. Update the server software to Purpur 1.21.11 using the same world.
5. Start the server.
6. Travel to the previously generated Trial Chambers.
7. Attempt to open vaults using valid trial keys.

Result:
Vaults do not activate and cannot be opened.

Additional confirmation:

• Regenerating the affected chunks using //regen fixes the issue.
• Manually breaking and replacing the vault block fixes the issue.
• Vaults in newly generated Trial Chambers work as expected.

Purpur version

This server is running Purpur version 1.21.11-2553-HEAD@5b4cbcc (2026-01-04T22:22:17Z) (Implementing API version 1.21.11-R0.1-SNAPSHOT)

• You are running the latest version
  Previous: 1.21.11-2552-6238ebf (MC: 1.21.11)

Agreements

• I am running the latest version of Purpur available from https://purpurmc.org/downloads.
• I have searched for and ensured there isn't already an open issue regarding this.
• I ticked all the boxes without actually reading them
• My version of Minecraft is supported by Purpur.

Other

This appears to be related to legacy block entity / NBT data of vault blocks generated before the update.

The affected world was originally generated on Minecraft 1.21.8 and then updated through multiple minor versions (1.21.10 → 1.21.11).

Trial Chambers vaults generated on earlier 1.21.x versions appear to contain legacy block entity data that is not properly migrated when loaded on Purpur 1.21.11.

Server environment:

• Previous version: Paper 1.21.10
• Current version: Purpur 1.21.11
• Java 21
• World was not modified between updates

[YouHaveTrouble]

Can you test if it happens on paper server?
I don't recall purpur having any patches related to vaults nor to data migration for blocks like that.

[tabatintores]

Can you test if it happens on paper server? I don't recall purpur having any patches related to vaults nor to data migration for blocks like that.

this problem also appears on paper. What should I do?

[granny]

Can you test if it happens on paper server? I don't recall purpur having any patches related to vaults nor to data migration for blocks like that.

this problem also appears on paper. What should I do?

You'll want to check the Paper GitHub issue tracker to see if it's been reported already by somebody else. If not, fill out a bug report for your issue. Make sure to share information about the Paper server you tested it on, NOT Purpur.