What causes "Chunk serializing error: {0}" in Pumpkin-MC/Pumpkin?

Read the embedded String message to identify which part of the chunk failed to serialize.

Pumpkin-MC/Pumpkin · error · ChunkWritingError

Chunk serializing error

Error message

Chunk serializing error: {0}

What it means

ChunkWritingError::ChunkSerializingError carries a String message describing a failure to serialize the chunk data structure into bytes before compression and writing. The library throws it when chunk data cannot be converted to the on-disk (NBT) representation.

Solutions

Read the embedded String message to identify which part of the chunk failed to serialize.
Validate chunk data (block states, section counts, entity data) before saving.
Update the world-format code if the chunk schema changed recently.
Log and skip the save for the offending chunk to avoid repeated failure.

Example fix

// before
writer.write_chunk(pos, &chunk).expect("serialize");
// after
if let Err(ChunkWritingError::ChunkSerializingError(msg)) = writer.write_chunk(pos, &chunk) {
    log::error!("chunk {pos:?} failed to serialize: {msg}");
}

Defensive patterns

Strategy: validation

Validate before calling

if chunk.get_block_count() > chunk.capacity() {
    return Err("chunk block count exceeds capacity before save");
}

Try / catch

if let Err(ChunkWritingError::ChunkSerializingError(msg)) = writer.write_chunk(pos, &chunk) {
    log::error!("serialize failed for {pos:?}: {msg}");
}

Prevention

Validate chunk invariants (sections, block states, entities) before saving.
Keep in-memory representation and world format versions aligned.
Log serialization failures with chunk coordinates to find offending game-logic bugs.

When it happens

Trigger: Saving a chunk whose data violates serialization invariants — e.g. blocks/entities/sections in a state the NBT writer cannot encode.

Common situations: Custom or modded chunk content, in-memory chunk state corrupted by a game-logic bug, version mismatches between world format and in-memory representation.

Understand the failure class

Background: json.Marshal / "failed to marshal" errors in Go: why "unsupported type" happens and how to fix it — this error's family across 22 libraries.

Related errors

AI-assisted analysis of Pumpkin-MC/Pumpkin@8d4639e25a (2026-09-09). Data as JSON: /api/errors/0b3737fa2931cc77. Report an issue: GitHub.

Appendix: source

Thrown at crates/pumpkin-world/src/chunk/mod.rs:50

    #[error("Invalid header")]
    InvalidHeader,
    #[error("Region is invalid")]
    RegionIsInvalid,
    #[error("Compression error {0}")]
    Compression(CompressionError),
    #[error("Tried to read chunk which does not exist")]
    ChunkNotExist,
    #[error("Failed to parse chunk from bytes: {0}")]
    ParsingError(ChunkParsingError),
}

#[derive(Error, Debug)]
pub enum ChunkWritingError {
    #[error("Io error: {0}")]
    IoError(std::io::Error),
    #[error("Compression error {0}")]
    Compression(CompressionError),
    #[error("Chunk serializing error: {0}")]
    ChunkSerializingError(String),
}

#[derive(Error, Debug)]
pub enum CompressionError {
    #[error("Compression scheme not recognised")]
    UnknownCompression,
    #[error("Error while working with zlib compression: {0}")]
    ZlibError(std::io::Error),
    #[error("Error while working with Gzip compression: {0}")]
    GZipError(std::io::Error),
    #[error("Error while working with LZ4 compression: {0}")]
    LZ4Error(std::io::Error),
    #[error("Error while working with zstd compression: {0}")]
    ZstdError(std::io::Error),
}

// Clone here cause we want to clone a snapshot of the chunk so we don't block writing for too long

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