At some point, I noticed there were no hostile mobs during the night. The same goes for deep mine shafts, no hostile mobs. Apart from monster spawners, those work.

I began do deactivate the mods I got installed, but none of them fixed the issue, however, the mobs startet spawning again, when I ran vanilla MC without Forge. So it seems to be a forge issue.

 

Running MC 1.7.2 with Forge 10.12.0.1027, however, I got the same issue with 10.12.0.1022 and 1023 too (didn't try the versions between '23 and '27, and I don't know about the versions before '22).

Java 1.7.0_51-b13 64Bit on Windows 7 64Bit

 

PS: I would have liked to attach the fml-client-latest.log, but I get an error "Cannot access attachments upload path!" when I try to

We dont allow random attachments, there are many other sites to host text with.

also, http://puu.sh/6T14y.jpg seems to be spawning just fine for me...

Make sure NOTHING else is installed.

I emptied the mods Folder, there is nothing else installed.

I tried a new world, there mobs DO spawn, just like your picture shows. Still, in my current world no mobs spawn once forge is enabled.

 

The fml-client-latest.log: http://pastebin.com/ALrvkDLi

Now I even removed the whole .minecraft folder and downloaded it again, installed 10.12.0.1027 afterwards, but mobs still don't spawn. Tried 10.12.0.1028 as well, but no spawning mobs there too.

Give me a copy of the world that is having issue.

Give me a copy of the world that is having issue.

I uploaded it here: https://www.hidrive.strato.com/lnk/ggDmuLIZ

Bah, seems my internet has taken a shit and I'm getting 0.5Mbps. So that'd take me roughly 8 hours to download. I've got a tech coming out tomarrow to take a look. Will look at your save once that's resolved.

 

Alright, fixed my internet myself whoot!

Took a look at your world, and I have to say with 100% certainty, it's NOT a Forge issue. And you DO have Hostile mobs in your world.

First thing I did was load your world in a clean Forge setup and then cycle the difficulty {Went to peaceful [which kills all hostible mobs] and then back to hard.} And immediatly got killed by a skeleton.

That told me you have mobs, but they are not around you.

So I made a box, and then wrote a command to teleport all monsters into that box.

This is what I saw:

If you notice, ALL the entities have something in there hands {and some are even wearing armor}

If a Monster is holding something in there hands they will NOT despawn, this is a mechanic in vanilla to prevent you loosing your items when a monster kills you and takes them.

So, basically you have hundreds of monsters running around caves clutching tightly to chicken eggs for some unknown reason.

All I can say is that one of your mods added it, No clue why.. Did you install a 'Chickens are gods!' mod or something?

So ya, basically, just cycle your difficulty to purge all monsters that are loaded, this does NOT kill the monsters that are NOT in the loaded chunks, but you can try running around in your world on peaceful to load all the chunks and kill them.

That indeed fixed the issue... thanks a lot

Still, why did the mobs spawn when I ran MC without forge?

And no, I didn't install a chicken gods mod... just VoxelMap, VillageInfo, ArmorStatus HUD and TreeCapitator... strange...

 

Well, thanks for your help