Affects Version/s: Minecraft 1.9, Minecraft 1.9.1 Pre-Release 3, Minecraft 1.9.2, Minecraft 16w14a, Minecraft 16w15a
Fix Version/s: Minecraft 1.10.1
Environment:OS: Windows 10 and Debian Jessie
All dropped items will display as stone. DataWatcher ID bug.
You just have to throw a splash potion before viewing any ground item (since your Minecraft was started) !
Then, go on a Minecraft Server (Vanilla, Spigot 1.9 or servers with 1.8/1.9 support) and drop an item on ground or throw a potion.
The item will be stone and the potion will display as water without real potion color.
In logs you will see:
- "Item entity XXX has no item?!"
- "ThrownPotion entity XXX has no item?!"
This bug append when EntityPotion class was loaded before EntityItem class (so, when you see throwed potion before item on ground).
That's because DataWatcher/EntityMetadata ID was based on class load order in some cases.
Code is from Spigot 1.9, but it's the same on 1.9 client :
This two codes call 'DataWatcher.a(EntityItem.class, DataWatcherRegistry.f);':
As you can see, variable i (the datawatcher index) is based on previous oclass value + 1.
So, if EntityItem load first, the id will be 5 and then when EntityPotion load the id will be 6.
But when EntityPotion load first the inverse occurs !
And when the inverse occurs the datawatcher ID was inverse and can't be synchronized with Minecraft servers.