Pumpkin-MC/Pumpkin · error

length exceeds

Error message

{name} length {len} exceeds {MAX_COLLECTION_LENGTH}

What it means

A generic guard in inventory_transaction decoding: collection_length() reads a VarUInt length for a named collection (e.g. 'inventory actions', 'requests') and rejects values above MAX_COLLECTION_LENGTH (1024). The message interpolates the collection name, actual length, and limit.

Solutions

1. Check for earlier field misalignment in the transaction packet; one bad read shifts all following lengths.
2. Reduce transaction batch sizes on the client to at most 1024 entries.
3. Verify client and server protocol versions for the inventory transaction layout.
4. Inspect the raw packet to see which named collection is oversized and why.

Example fix

// client before: batch everything in one packet
let actions = gather_all_pending_actions();
// after: split into chunks
for chunk in gather_all_pending_actions().chunks(1024) {
    send_transaction(chunk);
}

fn validate_collection_len(len: u32) -> Result<(), String> {
    const MAX: u32 = 1024;
    if len > MAX {
        return Err(format!("collection length {len} exceeds {MAX}"));
    }
    Ok(())
}

match InventoryTransactionPacket::read(buf) {
    Err(e) if e.to_string().contains("exceeds 1024") => {
        log::warn!("oversized collection in transaction packet: {e}; dropping");
    }
    other => other?,
}

When it happens

Trigger: Triggered whenever any collection in InventoryTransactionPacket (actions, legacy set item slots, requests, etc.) declares a VarUInt length greater than 1024.

Common situations: Malicious or buggy clients sending huge counts, stream desync after a prior misparse, mods generating oversized transaction batches.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• missing inventory transaction type
• missing inventory action data
• Unknown inventory transaction type
• item string array length out of bounds
• miss_count exceeds limit

AI-assisted analysis of Pumpkin-MC/Pumpkin@8d4639e25a (2026-09-09). Data as JSON: /api/errors/c5881803ed57d63c. Report an issue: GitHub.

Appendix: source

Thrown at crates/pumpkin-protocol/src/bedrock/server/inventory_transaction.rs:18

use std::io::{Error, ErrorKind, Read};

use pumpkin_macros::packet;
use pumpkin_util::math::position::BlockPos;

use crate::bedrock::network_item::NetworkItemDescriptor;
use crate::{
    codec::{var_int::VarInt, var_uint::VarUInt, var_ulong::VarULong},
    serial::PacketRead,
};
use pumpkin_util::math::vector3::Vector3;

const MAX_COLLECTION_LENGTH: u32 = 1024;

fn collection_length<R: Read>(reader: &mut R, name: &str) -> Result<usize, Error> {
    let len = VarUInt::read(reader)?.0;
    if len > MAX_COLLECTION_LENGTH {
        return Err(Error::new(
            ErrorKind::InvalidData,
            format!("{name} length {len} exceeds {MAX_COLLECTION_LENGTH}"),
        ));
    }
    Ok(len as usize)
}

pub const WINDOW_ID_INVENTORY: i32 = 0;
pub const WINDOW_ID_OFF_HAND: i32 = 119;
pub const WINDOW_ID_ARMOUR: i32 = 120;
pub const WINDOW_ID_UI: i32 = 124;

#[derive(Debug, PartialEq, Eq)]
pub enum InventoryActionSource {
    Container,
    World,
    Creative,
    Todo,

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