I don't know if this is a bug but no mobs are spwaning in my worlds no matter where I go the nether the end the mines and night time no mobs are spwaning

This is my first time using this bug tracker.

Please check if your difficulty is set to Peaceful.

It is on hard

And they are still not spwaning

Could you please add screenshots with the debug menu on (F3)?

And I did that command it did not work

Do you mean the command gave you an error, or did nothing happen?

Your render distance might be too low.

From http://minecraft.gamepedia.com/Spawn :

If the player's view distance or the server view distance in multiplayer is at 9 or below, mob spawning is severely reduced (or they despawn too quickly), and may result in the player encountering no mobs at all. Set the view distance to 10 or higher to ensure mobs spawn correctly.

According to your MultiplayerChunkCache seen in the screenshots, your render distance is set to 8.

I changed the render distance to 10 or higher but mobs still are not spawning.

I use the command again and nothing happened

Is this still an issue in the most recent versions (currently that is 1.12) of Minecraft? If so, please update the affected versions and help us keeping this ticket updated from time to time. If you are the owner/reporter of this ticket, you can modify the affected version(s) yourself.