Put the summary of the bug you're having here
What I expected to happen was...:
Zombies spawn near zombie spawner
What actually happened was...:
Zombies don't spawn near zombies spawner
Steps to Reproduce:
1. Wait near a spawner
2. The mob turn speedly
3. but no spawn...
Related issues
Comments
[Mod] Neko
migrated
… This is weirdly worded, but ok. Spawners require 2 things in order to spawn things. #1 No light around it. #2 Valid solid blocks underneath it. It cannot spawn on air. This might be the problem you are running into, but I'm not sure cause you didn't put any pictures in.
migrated
Word created in october 2013 (I don't remenber what version at this date...)
Upgrade from 18w16a to Prerelease Pre2
(idem from 18w16a to Prerelease Pre1)
[Mod] Neko
Duplicate of MC-129725
I suggest you load a backup from 1.12.2 or earlier.
migrated
Sorry for my english...
1. There is no light around
2. Solid block around the spawner ok
3. The spawner was ok before the Prerelease, I haven't modify anything.
migrated
I don't think it's a duplicate. The light is at "0".
What version was the world created in?
What versions have you upgraded to?