Issue:
A specific device experiences a network error (Internal Exception: io.netty.handler.codec.DecoderException: Failed to decode packet 'clientbound/minecraft:custom_payload'
) when attempting to join a Minecraft 1.21.1 server with the deflate
region file compression enabled. The device was previously able to join the server without issues, but after multiple connection attempts, the error occurs (not consistently reproducible). Other players can join the server without problems while the affected device encounters the error. No crash report is generated since the client does not fully crash; instead, the player is disconnected immediately after joining. Server logs show no errors—only the player joining and disconnecting abruptly.
Workaround:
Changing region-file-compression=deflate
in server.properties
to any non-default value resolves the issue, allowing the affected device to join the server. This behavior has been consistently reproduced in at least 6 tests.
Steps to Reproduce:
Set
region-file-compression=deflate
inserver.properties
.
Attempt to join the server with the affected device multiple times.
Observe the
DecoderException
error.
Change
region-file-compression
to a non-default value, and the device can join successfully.
Invalid, outdated and modded.