Starting in version 1,21.9 and also currently 1.21.10, light will not update/propagate to neighboring chunks in some places. I’ve only noticed this in the end dimension and particularly in the areas just outside the main end island. Its not just a client light glitch, endermen will spawn on the server in the areas that should be lit from thier neighboring chunks creating problems for farms that are supposed to be spawnproofed. These are old chunks that were built on many versions ago and worked fine before 1.21.9. (I paved and lit up a large area 4000x4000 give or take in my end dimesion last year. See screenshots)
Server restarts do not fix. Upgraded to 1.21.10, problem persists.
Was able to reproduce the problem in single player both on a copy of the server world, and on a brand new world where I made a flat area that was lit in a similar way to what was on my server (screenshots).
Environment
Server: Intel Core i7 10700 2.9ghz, 32 GB Ram, 64 bit Windows 10 Pro, Java 22.0.1
Minecraft java dedicated server 1.21.10, modded (fabric, carpet)
Client: Intel Core i9 10850k 3.6ghz 64GB Ram, 64 bit Windows 10 Pro, Java 21.0.5
minecraft java modded (fabric,carpet,worldedit,malilib,litematica,minihud,tweakeroo)
Thank you for your report!
However, this issue is Invalid.
Your game, launcher or server is modified.
If you can reproduce the issue in a vanilla environment, please recreate the issue.
Any non-standard client/server/launcher build needs to be taken up with the appropriate team, not Mojang.
A world which had previously been opened with a modified client might be corrupted. Please try reproducing the issue in a newly generated world.
Any plugin issues need to be addressed to the creator of the plugin or resource pack.
If you have problems on large servers like Hypixel, please contact them first as they run modified server software.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support (Technical Issues) – 📧 Microsoft Support (Account Issues)
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki