Where the mobs spawn?

[FTnGroot]

I have been trying to create a cow farm with spawners, I saw that passive mob should only spawn in grass but they are spawning in the air, is there any way they only spawn in grass.

Sorry for any mistakes english it's not my first language.

 

[rew]

I'm fairly sure they should only spawn on the grass. How are they spawning in the air, on some kind of block or just in the middle of nowhere?

 

[FTnGroot]

They are spawning in the middle of nowhere and dropping out to void

 

[Swrds]

Mobs spawn around 3 blocks radius of your spawner, the mob spawning forum post is outdated. Send me a screenshot of your current farm on discord and i’ll try help you out if you want :D Swrds#0001

 

[rew]

They are spawning in the middle of nowhere and dropping out to void

Make sure to cover more ground with the grass, then.