The warning log :

Using :

• reproduced on protocol lib versions 4.7.0 and 4.7.1
• holographic display last version 2.4.8
• beautyquest last version 0.19
• airplane 1.17

I can not reproduce it, just lauching my server with theses 3 plugins at least and get this warn every x seconds (randomly but very often)

As mentioned in filoghost/HolographicDisplays#499, the specific issue shown by OP has been fixed by HolographicDisplays in version 2.4.9.

Funny because now it is back to the previous protocol setting for 1.17.1 and even if you do use the previous setting, it doesn't destroy the entity

I had the same problem. To reproduce do this: public void sendRealDespawnPacket(Player reciver) { PacketContainer deSpawnPacket = new PacketContainer(PacketType.Play.Server.ENTITY_DESTROY); WrapperPlayServerEntityDestroy deSpawnPacketWrapper = new WrapperPlayServerEntityDestroy(deSpawnPacket); System.out.println(knocked.getEntityId()); int[] idlist = new int[]{knocked.getEntityId()}; System.out.println(Arrays.toString(idlist)); try { deSpawnPacketWrapper.setEntityIds(idlist); ProtocolManager pm = ProtocolLibrary.getProtocolManager(); pm.sendServerPacket(reciver, deSpawnPacket); } catch (InvocationTargetException e) { e.printStackTrace(); } } version of protocollib:

If u want to make despawn packet work on 1.17 do deSpawnPacket.getModifier().write(0, new IntArrayList(new int[]{ENTITYID}));