spawnmonsters false not working

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It's doMobSpawning, see https://minecraft.gamepedia.com/Commands/gamerule

will animals still spawn?

I do not want to run separate server with settings spawn-monsters false.

I do not want monsters from monsterspawners. Also how can i disable hostile mobs in singleplayer? I can not disable monsters in easy difficulty with command /gamerule spawnmonsters false.

@unknown: This site is a bug tracker, not a forum or tech support. Please go to https://www.reddit.com/r/Minecraft/

I sent feedback. This command gamerule spawnmonsters false does not work. Game version is 1.12.2. Also command is missing in latest snapshot.

There is no gamerule spawnmonsters. If you issue that, that has the same effect as when you issue /gamerule MaryHadALittleLamb: Nothing.

Did you even read the wiki article linked above?