Phantom light sources in mob farms


Hey all !

Recently the 1.13.2 server i play on upgraded to PaperMc.
We have had great improvents with lag on the server !

But since the Upgrade some off our players noticed that the spawnrates in mobfarms where quite low.
After some investigating one off the staff members saw that there was light coming from random spots like there was a torch there , but there are no light sources anywhere.

Does anyone know a solution to this problem?

Thanks in advance for taking your time reading this !


I believe that aikar was going to revert a patch to see if it had any impact on this, but it was one of those “highly unlikely” things, i’ve never been able to reproduce, best suggestion is to allow random light updates in spigot.yml, but be warned that that might cause performance issues as the light needs to be recalculated in affected chunks, spigots patch for that ends up mistreating light updates which can cause issues


I added a world config to paper.yml “optimize-light”, try setting this to false and see if it helps.