Pumpkin-MC/Pumpkin · error · PacketEncodeError

Compression failed

Error message

Compression failed {0}

What it means

`PacketEncodeError::CompressionFailed` is returned when the zlib/flate2 compressor fails while compressing an outgoing packet. The underlying compressor message is carried in the variant. This indicates the encoder could not produce a compressed frame.

Solutions

1. Check server memory availability — compression failures often stem from allocation failures.
2. Verify the configured compression level is in the valid 0-9 range.
3. Retry encoding once; if it recurs, restart the encoder/compressor state.
4. Report with the inner message if it persists, as it may indicate a flate2 backend issue.

match write_packet(&packet, version, &mut out) {
    Ok(()) => {},
    Err(PacketEncodeError::CompressionFailed(msg)) => {
        log::error!("compression failed: {msg}; retrying uncompressed or dropping packet");
    }
    Err(e) => return Err(e.into()),
}

When it happens

Trigger: Calling the packet encoder with compression enabled and the flate2 `write`/compress call returning an error — typically an allocation failure, an invalid configured compression level, or corrupted encoder state.

Common situations: Memory pressure in a long-running server; a bad compression level configured; reusing a compressor object across failed states.

Related errors

• Failed to verify username
• Invalid compression Level
• You are banned from Authentication servers
• Packet exceeds maximum length
• Writing packet failed

AI-assisted analysis of Pumpkin-MC/Pumpkin@8d4639e25a (2026-09-09). Data as JSON: /api/errors/2509e81bacf04394. Report an issue: GitHub.

Appendix: source

Thrown at crates/pumpkin-protocol/src/lib.rs:293

pub trait BClientPacket: Packet {
    fn write_packet(&self, writer: impl Write) -> Result<(), Error>;

    fn serialize_packet(&self) -> Result<Bytes, Error> {
        crate::bedrock::packet_encoder::serialize_packet(self)
    }
}

pub trait BServerPacket: Packet + Sized {
    fn read(read: impl Read) -> Result<Self, Error>;
}

/// Errors that can occur during packet encoding.
#[derive(Error, Debug)]
pub enum PacketEncodeError {
    #[error("Packet exceeds maximum length: {0}")]
    TooLong(usize),
    #[error("Compression failed {0}")]
    CompressionFailed(String),
    #[error("Writing packet failed: {0}")]
    Message(String),
}

#[derive(Error, Debug)]
pub enum PacketDecodeError {
    #[error("failed to decode packet ID")]
    DecodeID,
    #[error("packet exceeds maximum length")]
    TooLong,
    #[error("packet length is out of bounds")]
    OutOfBounds,
    #[error("malformed packet length VarInt: {0}")]
    MalformedLength(String),
    #[error("failed to decompress packet: {0}")]
    FailedDecompression(String), // Updated to include error details
    #[error("packet is uncompressed but greater than the threshold")]

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